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48783 



SCREEN YOUR TELEPHONE CALLS ELECTRONICAL 




777 



ECHNOLOGY - VIDEO - STEREO - COMPUTERS - SERVICE 



DIGITAL 
CIRCUIT 
SIMULATION 
USING SUSIE 

Are breadboards 
becoming a thing 
of the past? 



lll 71896%S783 M! 1 



1 2 



BUILD THIS BENCHTOP 
FREQUENCY COUNTER 




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It's inexpensive, 
and easy to build, 
yet gives performance 
over 1GHz 



BUILD THIS 
HI-TECH 
CHRISTMAS CARD 

Frequency-selectJve 
filters help create a 
spectacular display 



CHOOSING THE RIGHT 
TEST PROBE 

The right probe can 

really make a 

difference 



• ' • T-i : * i i * 



S2.95 U.S. 
$3.75 CAN 



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FLUKE AND PHILIPS 



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THE GLOBAL ALLIANCE IN TEST & MEASUREMENT 



- 




PHILIPS 



More than two million users agree: the 

Fluke 70 Series handheld digital multimeters 
are simply the best. 

These originals have become classics. And 
the reasons are simple. 

They are accurate and easy to use. Features 
made popular by the 70 Series-like fast 
autoranging, continuity beeper, and quick 
diode test-are now standards in the industry. 

Other 70 Series features stand alone. Touch 
Hold®, for example, locks the reading on 
the display and signals you with a beep. So 



you can keep your eyes on the circuit and 

probes. 

The 70 Series are built without compromise. 
All current ranges are fully fused. The 
resistance function is overload protected to 
500V. No detail has been overlooked in 
making these rugged and reliable meters 
the first choice of two million professionals. 

Made in the USA using state-of-the-art man- 
ufacturing methods, every Fluke 70 Series 
multimeter is backed by a 3-year warranty. 
Another first in the industry, 



Choosing the best handheld multimeter is 
very simple. Pick up the Fluke 70 Series at 
your Fluke distributor today. Or call 
1-800-44-FLUKE, ext 33, for a free 

brochure. 

Jotin Flutt Mlo Co.. Inc. P.O. Bo* 9O90. Ewerell, WA 98206. U.S.: 

(206) 356-5400 Canada: H15] 8SO-7WO Other countries (236) 
356-5500. 6 1990 John Flute Mlrj. Co., Inc. All nflhts reserved 
Ad no. 0701-F70 

FROM THE WORLD LEADER 
IN DIGITAL MULTIMETERS. 



FLUK 



CIRCLE 121 ON FREE INFORMATION CARD 






December 1990 ei,„ 



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Vol. 61 No. 12 




33 BENCHTOP FREQUENCY COUNTER 

Build an inexpensive, full-function frequency counter. 
Carl Bergquist 

40 THE CHRISTMAS CARD 

Our electronic Christmas tree makes a bright holiday greeting! 
Ron Holzwarth 

48 TELEPHONE CALL SCREENER 

Put an end to junk calls. 
John G. Keller 



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PAGE 57 




63 CHOOSING THE RIGHT TEST PROBE 

It's important to know which probe meets your testing needs. 
Bill Hansen 



EHMSM 




57 SUSIE 

Simplify digital design using SUSIE, the Standard Universal 
Simulator for Improved Engineering. 
TJ Byers 

86 COMPUTER CONNECTION 

An electronics-lab simulation program. 
Jeff Holtzman 




PAGE 63 



EEMSME 



6 VIDEO NEWS 

What's new in this fast- 
changing field. 
David Lachenbruch 

24 EQUIPMENT REPORTS 

Radio Shack's Micronta Voice 
Meter. 

69 HARDWARE HACKER 

Santa Claus machine update, 

and more! 

Don Lancaster 




76 AUDIO UPDATE 

The amplifier- transfer-function 

controversy. 

Larry Klein 

78 DRAWING BOARD 

Keeping the DTMF-generator 

circuitsimple. 

Robert Grossblatt 

81 IC SPOTLIGHT 

What's new in IC and systems 

development. 

Mike Mullin 



100 Advertising and Sales 
Offices 

100 Advertising Index 

8 Ask RE 
49 Free Information Card 
16 Letters 
91 Market Center 
30 New Lit 
26 New Products 

4 What's News 



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Tis the season. . .when we all 
wrack our brains to come up with 
unique gift ideas. This year, we've 
made it easy, with a project that's 
right in the spirit of the holiday sea- 
son. Our Electronic Christmas Tree 
is really a PC board whose traces 
form the branches. Multi-colored 
LED's look like Christmas-tree 
lights, and blink in time with any 
kind of audio. Turn to page 40 to see 
our festive project that makes a 
great holiday greeting or window 
display. And if your wallet's feeling 
the pinch of holiday shopping, you'll 
appreciate our Benchtop Frequency 
Counter. Half the price of commer- 
cial models, it offers an impressive 
array of functions. The versatile, 
easy-to-use instrument is based on 
the Intersil ICM7216C. To find out 
more, turn .to page 33. 




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THE JANUARY ISSUE 

GOES ON SALE 

DECEMBER 4. 

BUILD A MACINTOSH 

Use an Apple motherboard to build your own Macintosh computer 
— for a fraction of what Apple charges. 

R-E's E-Z SHORTWAVE RADIO 

Build it, then modify it to receive any frequency that you're interested in! 

NEGATIVE-ION GENERATOR 

Experiment with high-voltage electronics and the effects of negative ions. 

BATTERIES 

A review of rechargeable-battery technology. 

1990 ANNUAL INDEX 

A complete listing of our feature articles and departments. 

As a service to readers, RADIO-ELECTRONICS publishes available plans or information relating to newsworthy products. 
techniques and scientific: and technological developments. Because of possible variances in the 'quality and condition of 
materials and workmanship used by readers. RADIO-ELECTRONICS disclaims any responsibility for the safe and proper 

functioning of reader-built projects based upon or from plans or information published in this magazine. 

Since some of the equipment and circuitry described in RADIO-ELECTRONICS may relate to or be covered by U.S. patents, 
RADIO-ELECTRONICS disclaims any liability for the infringement of such patents by the making, using, or selling of any such 
equipment or circuitry, and suggests that anyone interested in such projects consult a patent attorney. 

RADIO-ELECTRONICS. (ISSN 0033-7B6B December 1990. Published monthly by Gemsbaek Publications, Inc.. 500-B Bi- 
County Boulevard. Farmingdale, NY 11735 Second-Class Postage paid at Farmingdale, NY and additional mailing uffaces. 
Second-Class mail registration No. 9242 authorized at Toronto. Canada. One-year subscription rata U.S.A. and possessions 
St 7.97. Canada S23.97, all other countries 626.97. All subscription orders payable in U.5A funds only, via international postal 
money order or check drawn on a U.S.A. bank. Single copies S2.95 1990 by Gemsbaek Publications. Inc. All rights reserved. 
Printed in U.S.A. 

POSTMASTER: Please send address changes to RADIO-ELECTRONICS, Subscription Dept.. Bcw 55115, Boulder, CO 
80321-5115. 

A stamped self-addressed envelope must accompany all submitted manuscripts and/or artwork or photographs if their return is 
desired should they be rejected. We disclaim any responsibility for the loss or damage of manuscripts and/or artwork or 
photographs while in our possession or otherwise. 



Electronics 



Hugo Gemsba c k (1 884- 1 967) founder 
M. Harvey Gemsbaek. 
editor-in-chief, emeritus 

Larry Stockier, EHF, GET. 
editor-in-chief and publisher 

EDITORIAL DEPARTMENT 
BHan C Fentort. editor 
Marc Sptwak, associate editor 
Daniel Goodman, technical editor 

Kim Dunleavy, 

assistant technical editor 
Terl Scadutct, assistant editor 
Jeffrey K. Holtiman 

computer editor 
Robert Grossblatt. circuits editor 
Larry Klein, audio editor 
David Lachenbruch 

contributing editor 
Don Lancaster 

contributing editor 
Richard D. Fitch 

contributing editor 
Kathy Terenzl, editorial assistant 

ART DEPARTMENT 
Andre Duzant. art director 
Injae Lee, illustrator 
Russell C. Tru olson, illustrator 

PRODUCTION DEPARTMENT 
Ruby M. Yee, production director 
Janice Box, 

editorial production 
Karen S. Tucker 

advertising production 
Marceila Amoroso 

producti on ass ista nt 

CIRCULATION DEPARTMENT 
Jacqueline P. Cheese boro 

circulation director 
Wendy Alanko 

c ircu latio n ana lyst 
Theresa Lombard o 

circulation assistant 
Michele Torrillo, reprint bookstore 

Typography by Mates Graphics 
Cover photo by Diversified Photo 
Services 

Radio-Electronics is indexed in 
Applied Science & Technology Index 
and Readers Guide to Periodical Liter- 
ature, 

Microfilm & Microfiche editions are 
available. Contact circulation depart- 
ment for details. 

Advertising Sales Offices listed 
on page 100. 



a/"% The 
JUV Aud.l ' 

\ W Bureau 

ol Circulation 





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WHAT S NEWS 




A review of the latest happenings in electronics. 



The "new" NESDA 

The entire by-laws of the National 
Electronics Sales & Service Dealers 
Association CNESDA) were replaced 
with new ones at membership voting 
sessions held last August at the an- 
nual National Professional Elec- 
tronics Convention (NPEC) in Las 
Vegas, NV. Although the rules were 
completely rewritten, the actual 
changes in NESDA operations are 
few t _and mainly involve shifting con- 
trol from the state to the national 
level. The new laws allow NESDA to 
control its own destiny as a national 
association instead of being con- 
trolled by state organizations. Under 
the new rules, NESDA will control the 
billing of all members, but will encour- 
age 'Associate" ventures with re- 
gional, state, and local organizations. 
Local billing will still be permitted un- 
der certain conditions. Other 
changes that were made included re- 
placing the NESDA House of Repre- 
sentatives and Regional Vice Presi- 
dents with a Board of Directors. 

Elections for several positions 
were held at the convention, which 
was attended by more than 600 peo- 
ple. Elected as president of NESDA 
was Cornelius C. ("Connie") Bell, re- 
tired owner of C.C, Beil Electronics in 
St. Louis, MO. Bill Warren, GET/ 
CSM, of Warren's Audio & Video Ser- 
vice of Knoxville. TN was elected vice 
president. The ten members of the 
Board of Directors were also chosen. 

Intense laser beam 

Researchers at Bellcore CMid- 
dletown Township, NJ) have dis- 
covered a way to focus 1 60 extremely 
small laser beams into a single, 
powerful beam. Separately, each sur- 
face-emitting laser is virtually invisible 
to the naked eye, measuring about 
one-tenth the diameter of a human 
hair, and does not generate enough 
power for useful applications. The en- 
ergy that can be harnessed from the 
experimental arrays, on the other 
hand, could be used on microchips in 
optical computers and neural net- 
works or possibly for creating holo- 
graphic images 




DR. ROBERT TINKER (LEFT), CHIEF SCIENCE OFFICER OF TECHNICAL Education 
Research Centers, a non-profit organization committed to improving science and mathe- 
matics education, was presented with the first Siemens Award for the Advancement of 
Science at the Computerworld Smithsonian awards event held at the National Building 
Museum in Washington, D.C. The innovative educator is credited with first introducing 
networked programs using computer technology into the science classroom. He has 
developed such influential programs as the National Geographic Kids Network, the Star 
Schools program, LabNet, and the Global Lab, which engages students, teachers, and 
scientists around the world in tackling ecological problems. According to Hans Decker 
(right), president of Siemens Corporation, "Dr. Tinker's vision of children as scientists, 
tackling real world problems, makes him the ideal recipient of this award." 



When the microscopic lasers are 
packed close together, they each re- 
ceive a uniform amount of electrical 
current and can "lase" in concert. 
Bellcore's array consists of surface- 
emitting lasers, which direct light up 
off the surface instead of horizontally, 
allowing many more lasers to be 
packed onto a single microchip. Ac- 
cording to Hoi Jun Yoo, the principal 
researcher, "Since you can place 
lasers anywhere on the surface of a 
chip, you can make the best of avail- 
able "chip real estate." The small 
lasers require about 10.000 times 
less space than semiconductor 
lasers used in similar limited applica- 
tions today. 

When etched onto a semiconduc- 
tor in a special array of 160 2-micron- 
diameter lasers spaced 0.2-microns 



apart (one micron equals a 40-mil- 
lionth of an inch), the vertical beams 
of light generated blend with one an- 
other through a phenomenon called 
"phase locking," whereby different 
optical fields overlap to create the 
equivalent of one light source. The 
result is the creation of one extremely 
narrow beam, analogous to several 
small streams feeding into a powerful 
river. 

The Bellcore experiment is the first 
time scientists have managed to suc- 
cessfully harness surface-emitting 
lasers to form a single laser light 
source. 

The research team is now working 
to integrate the prototype arrays with 
electronic devices that will be able to 
accurately control and steer the di- 
rection of the beam. R-E 



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VIDEO NEWS 



What s new in the fast-changing video industry. 



DAVID LACHENBRUCH 



• Who's No. 2? Philips has ended 
Zenith's long-time reign as one of the 
two largest suppliers of TV sets for 
the American market. The Dutch- 
owned company's four American 
brands — Magnavox, Sylvan ia, Phi- 
lips, and Philco- — aggregated 12.2% 
of American TV sales in the 1990 
model year (mid-1989 to mid-1990), 
topping Zenith's 11.65% to become 
America's second largest source of 
TVs, according to the annual market 
share survey conducted by Television 
Digest. Thomson Consumer Elec- 
tronics, a French-owned company, 
continued to be far and away the lead- 
er, its RCA and GE brands aggregat- 
ing 22.5% of the market. 

Philips' advance marked the first 
time in the 23 years since the TV 
Digest survey has been conducted 
that the first two places weren't oc- 
cupied by the manufacturers of RCA 
and Zenith TV sets. Zenith is the only 
major U.S. -owned TV-set manufac- 
turer, although some 20 companies 
have U.S. TV assembly or manufac- 
turing plants. Strictly on the basis of 
brand names (as opposed to man- 
ufacturers), Zenith was still No. 2, 
following RCA, and Magnavox was 
the third most popular brand, fol- 
lowed by Sony, 

• Super-Interactivity. The ulti- 
mate in interactive laserdiscs has 
been demonstrated by Warner New 
Media, a part of Time Warner Inc. The 
12-inch disc will play for one hour per 
side Cas opposed to the 30 minutes 
normally associated with interactive 
discs). It can accommodate four si- 
multaneous video tracks with four se- 
lectable audio tracks, for a total of 16 
combinations. In one suggested ap- 
plication, a viewer could select any of 
four different views of the same 
event, with constant audio. The sys- 
tem can display subtitles in up to 15 
different languages. 

In addition to the main digital ster- 
eo channels, it can have 16-channel 
sound. The channels are mixable— 
for example, each channel could have 
a different instrument of the or- 
chestra. The videodisc could be used 



as a sort of super-CD — providing 
eight hours or more of audio. Al- 
though the new super-interactive disc 
will be compatible with existing laser- 
discs and players, it could have spe- 
cial encoded video and audio 
information available only to those 
with special players. Warner says 
that the super discs would use cur- 
rently available technology and the 
"LD-t-" players could cost less than 
$1,000. Pioneer and Denon helped 
develop the system, and they could 
introduce super players in 1991. 

• Lightvalve projection TV. 

When Hughes Aircraft embraces a 
product, it's usually a significant one. 
That's why the consumer-electronics 
industry pricked up its radar with the 
rumor that Hughes has a TV set. 
Hughes is keeping its mouth shut on 
this one. but it's known to be working 
with Samsung, the Korean TV man- 
ufacturer, on a new type of lightvalve 
TV projector. Although both compa- 
nies say nothing has been signed yet, 
there are some indications that a 
home product could emerge early in 
1992. No details are available on the 
system, except that it uses a single 
lightvalve in place of the traditional 
cathode-ray tubes and that the light- 
valve isn't a liquid-crystal device, or 
LCD. The system is said to be capa- 
ble of providing high-definition TV. 
This will be Hughes' second major 
foray into consumer electronics. Its 
Sound Retrieval System CSRS) super 
stereo audio is used with Sony TV's 
and is expected to be added to high- 
end RCA TV's within the next year. 

• Stili/motion camcorder. 

Quite possibly the biggest flop of the 
video era is the still-video camera. 
The reasons for its failure are easy to 
understand. Who would pay $600 to 
$1,000 and more for a still camera 
with low resolution and no practical 
system for making prints? Although 
still-video cameras have been suc- 
cessful in newspaper photography 
because the pictures can be trans- 
mitted by telephone, they have failed 
to impress consumers because they 



have been more expensive than mov- 
ing-picture camcorders, and far more 
costly than film cameras. 

Along comes Philips with a super- 
idea. What's wrong with a combina- 
tion movie-and-still camcorder? A 
camcorder made in Philips' Japanese 
factory for the European semi-profes- 
sional market can make Super-VHS 
videos and "high-quality pho- 
tographic prints," according to the 
manufacturer. The camcorder uses a 
%-inch CCD sensor with a resolution 
of 700,000 pixels, and is claimed to 
deliver a picture with more than 450 
lines of horizontal resolution. Philips 
will offer a companion printer. It 
makes good sense to envision future 
still-picture systems as add-ons to 
movie camcorders, rather than sepa- 
rate products. Although Philips says 
that it has no plans to offer the movie/ 
still camcorder in the United States, 
or as a consumer product, that 
seems to be a logical next step. 

• A government picture tube. 

The Pentagon's Defense Advanced 
Research Projects Agency (DARPA) 
has awarded Zenith a contract to de- 
velop its Flat Tension Mask CFTM) 
technology into a cost-efficient high- 
definition picture tube. Zenith's FTM 
system, currently used only for high- 
priced computer monitors, has a 
completely flat window-glass facep- 
late, behind which is a shadow mask 
held under tension, assuring better 
color rendition because the mask 
doesn't expand. Reflections are also 
held to a minimum because the face- 
plate is absolutely fiat and the glass is 
treated with a special coating. The 
government contract is designed to 
fund a major cost reduction in the 
new tube. Zenith maintains that the 
phosphors on the tubes can be 
printed by a silk-screening process, 
as opposed to the extremely expen- 
sive photographic system currently 
used for color tubes. If Zenith suc- 
ceeds in fulfilling the Pentagon con- 
tract, it should result in a major 
improvement in picture tubes, lower 
costs, and, eventually, a new type of 
high-definition display. R-E 




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Write to Ask R-E, Radio- Electronics, 500-B Bi-County Blvd., Farmingdale, NY 11735 



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o 



VOLTAGE CONVERTERS 

I have a bunch of tools and 
some stereo equipment that 
was designed to run on the 
standard European supply of 
220 volts, 50 Hz AC. Isn't 
there some way I can easily 
make, buy, or otherwise ac- 
quire a transformer that will let 
me operate those devices off 
120 volts, 60-Hz AC?— A. 
Sfakianos Placitas, NM 

There are lots of place9 to get 
transformers that turn 220 volts AC 
into 110 volts AC, and they should 
work when their supply connections 
are reversed as well, but only for the 
voltage, not the frequency. You indi- 
cated in your letter that the frequency 
difference wasn't important for the 
equipment you wanted to use so I 
don't understand why you're having 
so much trouble. 

There are two basic types of com- 
mercially available converters used 
for converting 220 volts AC to 1 1 
volts AC, and they're sold in just 
about every electronics store; even 
Radio Shack carries them. With a 
transformer I use, I can turn the sup- 
ply leads around and step up the line 
voltage from 1 1 volts AC to 220 volts 
AC (actually 120 to 240). There isn't 
any problem in doing that as long as 
you make sure you have the right type 
of voltage converter. 

Converters are made with either 
transformers or diodes. You can tell 
the difference between them when 
you're looking at the package by the 
weight and the wattage rating. Trans- 
former-based converters are much 
heavier than the diode-based ones 
and usually have a maximum rating of 
about 50 watts or so. The package 
information should list them as being 
suitable for electronic equipment, 
battery chargers, camera flash units, 
and so on. Since there's a trans- 
former inside the package, the volt- 
age is actually divided in half, Cor 
doubled, when you use it backwards). 
The output of those converters is a 
sinusoid. 

Diode-based converters are much 
lighter, and even though the package 



is the same size, they usually have a 
maximum rating of 1000 or 1500 
watts. You'll find them recommended 
for things like heaters, lamps, and so 
on. If you try and use one of those 
appliances with a transformer oper- 
ated converter, you'll probably wind 
up destroying both the converter and 
whatever you have plugged into it. 
With the diode-based converters, 
you cant turn them around and ex- 
pect to double the input voltage. 

Generally, diode-based converters 
only produce half-wave rectified AC 
instead of a full sine wave, and they 
don't cut the voltage in half either. As 
with any diode voltage drop circuit, 
the output is .67 times the input volt- 
age. If you put 220 volts AC across 
the input, you're going to get about 
148 volts AC at the output. That may 
not be much of a problem for most 
resistive loads, but you should realize 
that overdriving a heater is going to 
make it hotter than it was designed to 
be and that can cause a real problem, 

ALARM SYSTEM BACKUP 
I've designed an alarm cir- 
cuit for my house that's 
powered by line voltage but I 
want it to switch over to back- 
up batteries if and when the 
power fails. The control part of 
the circuit is the only section 
that has to be constantly 
powered. I'm not worried 
about lights and other high 
current devices since I have a 
commercial unit for that part 
of the system. Do you have a 
simple circuit that can provide 
the battery backup? I only 
need 100 milliamps or so. — G. 
Benjamin Indianapolis, IN 

Having a fail-safe power-supply for 
a home alarm system is a good idea 
and, if you think of it, is probably the 
most important part of the alarm sys- 
tem. Fortunately, it's also one of the 
easiest things to add to the circuit. In 
your case, it's even easier, since you 
designed the alarm-control circuit 
yourself. 

There are several ways to add a 
battery backup to a circuit, but since 



you're only looking for 100 milliamps. 
you can keep it simple and the back- 
up circuit can be made so small you'll 
be able to easily find room for it in 
your existing enclosure. 

The circuit shown in Fig. 1 is a sim- 
ple design that can do the job. When 
the line voltage is available and oper- 
ating, D2 is reverse- biased and cur- 
rent flows into the batteries through 
R1, the current limiter for the nickel- 
cadmium CNi-Cd) batteries, or what- 
ever type of rechargeable battery you 
want to use. If the main power is dis- 
connected (inadvertently by you or 
intentionally by a burglar), D2 is for- 
ward-biased and battery power is 
available for the alarm circuit. By 
adding D1 to the circuit, you can keep 
the battery from powering other cir- 
cuitry that's not essential to keeping 
the alarm system active. 



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FIG. 1— THIS SIMPLE BATTERY backup 
circuit can be used to power a control 
circuit for art alarm system. 



The particular diode you should 
use for D2 depends on the amount of 
power you want to draw from the bat- 
tery when the main power is discon- 
nected. If you're sure that you'll never 
need more than 100 milliamps, you 
can probably get by with a small 
1N914 diode but, if there's a chance 
you might draw more current, or you 
just want to play it safe, you're better 
off with something like a 1N4001. 

If you use Ni-Cd batteries, you'll 
need a constant trickle-charging cur- 
rent. You should select R1 to limit the 
charging current to the battery's 
C/10 rating, which is 10% of the ca- 



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pacity of the battery. In aC/10 rating, 
"C" is the charge capacity in amp- 
hours, and "10" is the number of 
hours the battery can supply useful 
power. Therefore, the capacity divid- 
ed by that operating interval equals 
the maximum current safely drawn 
from or supplied to the battery. The 
trickle current charge, l c . must be 
less than or equal to the maximum 
safe current drawn through the bat- 
tery. 

The value of R1 can easily be calcu- 
lated using 

R1=[(V c -(0.6 volts + V b )]/I c 

where V c is the circuit voltage. V b is 
the battery voltage, and l is the 
charging current. 

This is just a straight application of 
Ohm's Law. The reason it seems 
more complex is that you have to sub- 
tract the 0.6 volt-diode drop and bat- 
tery voltage from the supply voltage. 

The capacitor in the circuit is used 
to filter any voltage glitches and also 
to provide a few seconds of power if 
you want to change batteries. 

TWO HARD DISKS 

I have an AT-class computer 
with a hard disk and am trying 
to add a second hard disk. The 
controller card can work with 
two hard disks, but I'm not 
having any luck connecting 
the cables. No matter what I 
do, the computer never recog- 
nizes the second hard disk. — 
W. Meredith Philadelphia, PA 

If you're installing the second drive 
simply to increase capacity, maybe 
you should consider buying a single 
new hard drive with at least double 
the memory of your present one. Not 
only will that give you extra room in- 
side your cabinet for other add-ons 
such as tape drives, but you might 
also benefit from increased overall 
operating speed — your old drive may 
not be as fast as the newer ones. You 
can keep your old drive for emergen- 
cy backup, or you can sell your old 
drive to someone who doesn't have 
one. However, if you 're determined to 
add a second drive, read on. 

In order to have two hard disks in 
your computer, you have to tell the 
computer the second hard disk is 
there and then you have to cable it so 
the computer can find it. 

Since you have an AT computer, 
you have to run the setup utility and 
set the correct type for the second 



hard disk. How that is done depends 
on the BIOS you have since some of 
them have the setup utility in ROM 
while others require that you run a 
program on a disk, such as the IBM 
AT diagnostics. Be sure and set the 
type correctly since an incorrect 
number there can damage the hard 
drive. 

Once you have that done, you have 
to physically connect the drive to the 
computer and that involves four 
things: 

1 . A power cable has to be connected 
to the drive. 

2. A separate data cable Cthe thin 
one) has to be connected from the 
controller card to the drive. 

3. The control cable Cthe fat one) has 
to be connected to the drive. 

4. The drive select jumpers on the 
back of the hard drive have to be set 
to match the type of control cable 
you're using. 

The first two operations are simple 
and just about the only thing you have 
to watch out for is the cable's orienta- 
tion. Pin 1 on the controller card has 
to be connected to pin 1 on the drive's 
edge connector. 

The last two items on the list go 
together since the drive select 
jumper on the back of the disk has to 
be set according to the type of con- 
trol cable you're using. 

The first hard disk in the system, 
(your original one), should be at- 
tached to the connector at the end of 
the control cable and the second hard 
disk, (your new one), should be at- 
tached to the connector in the middle 
of the cable. 

If there's a twist in the wires be- 
tween the connectors for the two 
hard disks, the drive select jumpers 
for both hard disks should be set in 
the second position (sometimes 
marked as DS2.) If there's no twist in 
the cable, the drive at the end (your 
original one) should have the jumper 
set in the first position and the drive in 
the middle of the cable, (your new 
one), should have the jumper in the 
second position. 

The terminating resistor should be 
removed from the new drive in the 
middle of the cable and left on the 
original drive at the end of the cable. If 
you can't find the terminating resistor 
or have a hard time trying to remove 
it, don't worry about it. I've seen sev- 
eral machines in which both drives 
had the terminating resistors left in 
and everything worked fine. R-E 






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what was to be an embassy and private 
residence into the most sophisticated re- 
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known. The building had to be torn 
down in order to remove all the bugs. 

Stolen Information 
The open taps from where the informa- 
tion pours out may be from FAX's, com- 
puter communications, telephone calls, 
and everyday business meetings and 
lunch time encountets. Businessmen need 
counselling on how to eliminate this in- 
formation drain. Basic telephone use cou- 
pled with the users understanding that 
someone may be listening or recording 
vital data and information greatly reduces 
rhe opportunity for others to purloin 
meaningful information. 



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The professional discussions seen on 
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how to look for a bug, where to look for a 
bug, and wfiar to do when you find it? 

Bugs of a very small size are easy to 
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Today you may have used a telephone 
handset that was bugged, it probably 
contained three bugs. One was a phony 
bug ro fool yon inro believing you found a 
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The professional is not without his 
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Some of this equipment can be operated 
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The professionals viewed on your tele- 
vision screen reveal information on the 
latest technological advances like laser- 
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snoop on. The professionals disclose that 
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This advertisement was not written by 
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15 



LETTERS 



Write to Letters, Radio- Electronics, 5QQ-B Bi-County Blvd., Farmingdale, NY 11735 



LOGIC ANALYZER REANALYZED 

The review of the Photronics low- 
cost logic analyzer (.Editor's Work- 
bench. Radio-Electronics, Au- 
gust 1990) does a terrible injustice to 
the product in stating that its "low 
speed" and "8-bit operation" are in- 
sufficient. That fact is that its speed 
and data width are usually more than 
adequate for the application areas for 
which it was designed. 

The LA1 is primarily intended for 
digital troubleshooting in areas that 
require more than a dual-trace os- 
cilloscope, a digital voltmeter, and a 
logic probe while not requiring the 
power, expense, and complexity of a 
typical logic analyzer designed for mi- 
croprocessor applications. When an 
actual situation places the designerin 
that predicament, the need for a me- 
dial solution becomes obvious, A few 
examples that prompted the design 
of the LAI are stepper- motor logic 
circuits, remote-control circuits using 
the popular 40-kHz IR encoding, and 
countless applications in the non-mi- 
croprocessor prototype circuits 
breadboarded by the professional as 
well as hobbyists and students. Many 
of those applications do not require 
all eight data channels or the full 
bandwidth of the LAI. 

Perhaps the label "logic analyzer" 
automatically conjures up the thought 
of complex, high-speed, wide-bus mi- 
croprocessor analysis; nonetheless, 
that is the most appropriate label for 
the LAI, which completely accom- 
plishes its design goal by introducing 
a cost-effective means of obtaining 
that worthy capability at the other end 
of the spectrum. 
DALE NASSAR 
PRESIDENT, PHOTRONICS 
Amite, LA 

Perhaps I should have said "insuffi- 
cient for the things people normally 
g use logic analyzers for, " which does 
z not include IR decoding, stepper- 
£ motor circuits, and so on. I liked the 
o device quite well as a teaching aid, 
3 but I remain skeptical of its utility out- 
5 side the educational environment. 
5 That is not to denigrate the device; a 
a: balanced review must point out both 



the strengths and the limitations of a 
product. — Jeff Holtzman, Computer 
Editor 

CABLE SCRAMBLING 

I read with interest Robert 
Grossblatt's Drawing Board column, 
entitled "Scrambling and Macrovi- 
sion," in the July issue of Radio- 
Electronics. I am only sorry that, as 
a new subscriber, I have missed some 
very important information in earlier 
Issues. 

However, having worked for the 
"Phone Factory" for a number of 
years before retiring, I am well ac- 
quainted with COAM (customer 
owned and maintained) equipment 
and the pitfalls of the "rules." With 
divestiture, as Mr. Grossblatt said, 
we can now connect "most any- 
thing" to the line on the COAM side 
of the RJ block— as long as it doesn't 
"upset" or interfere with the net- 
work. Cable TV, as a franchised com- 
pany, should operate under the same 
rules. If they do not want a channel to 
be available to me, then they 
shouldn't put it on the network to 
begin with. 

The power company doesn't say 
that you have to pay higher rates if 
you have a microwave oven, hair dry- 
er, TV. etc., and I see no reason for 
any utility to have special con- 
cessions. So if they don't want me to 
have what is on the network, then 
don't provide it and trap it out — make 
me the responsible party, not them. 
DELBERT McMULLEN 
Independence. MO 

THE "LONG RANGER" 
I am responding to the article 
"Whatever Happened to AM Radio?" 
(Radio-Electronics, September 
1990). After 38 years as a small-mar- 
ket chief engineer and announcer, I 
feel I have some understanding of 
AM/FM radio. 

A new business climate exists to- 
day. Most business firms in this rural 
area are chain outfits. They advertise 
little on radio. FM or AM, Ten years 
ago almost all were Mom-and-Pop 
concerns and, though some didn't 



contribute heavily, nearly all adver- 
tised, TV and cable were no competi- 
tion for commercials then or now. But 
they have captured a large portion of 
the audience. Today, the weekly 
newspapers, shoppers' guides, and 
sales flyers get the bulk of advertising 
dollars. 

There are too many AM stations, 
especially at night. We can receive a 
half dozen that are relatively free from 
interference. But one picture is worth 
a thousand words, so we watch TV at 
night. And some areas have too many 
stations, in the day and evening. 

The National Association of Broad- 
caster's (NAB) grand scheme to in- 
stitute the National Radio Systems 
Committee's (NRSC) pre-emphasis 
to AM is largely a wild idea, in my 
opinion, and will cause additional in- 
terference (albeit some improvement 
in the cheap sets with poor audio 
quality). The plan is to change back in 
the future, removing pre-emphasis. 
Why not attack the problem head on? 
Yes, even manufacture our own re- 
ceivers if the Japanese won't cooper- 
ate. We have the know-how. the 
facilities, and plentiful parts. 

AM radio, as we old-timers re- 
member it. is gone. But with some 
prudent managing it is far from dead. 
In fact, we just might see an AM re- 
surgence in the future — it is definitely 
the long ranger! 
GENE VINSON 
Thomasvilte, AL 

MORE ON AM RADIO 

Mr. Dexter's article about the prob- 
lems facing AM radio contained a se- 
rious technical error. Mr. Dexter 
wrote that AM transmissions are lim- 
ited to a bandwidth of 10 kHz, and an 
audio response upper limit of 5 kHz. 
Actually, the FCC has always allowed 
AM stations to transmit audio out to 
15 kHz (the same as FM radio), with a 
corresponding RF bandwidth of 30 
kHz. AM radio's poor sound quality is 
because almost all AM receivers 
have a 10-kHz bandwidth, limiting re- 
ceived audio response to 5 kHz. 

When broadcasting began, there 
was no such thing as "high fidelity." 



16 




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17 



No other training— 

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service computers 



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Accredited Member, National Home Study Council 



Many AM stations used standard 
telephone lines, which have upper 
limits of 5 kHz, to send audio from the 
studio to the transmitter. AM radios 
were built with narrow bandwidth IF 
filters to minimize interference. Even 
when high fidelity was introduced in 
the 1950s and 1960s, AM stations 
still used standard phone lines to link 
the studio with the transmitter. In the 
1980s, almost all stations converted 
to high-fidelity 15-kHz telephone 
lines, but AM radios were still built 
with narrow bandwidth s, due to the 
added expense entailed in a "wide- 
band" option. 

The standards proposed by the 
NRSC are intended as a compromise 
between interference and audio 
fidelity. Under the plan, AM stations 
will limit audio response to 10 kHz, 
thus limiting RF bandwidth to 20 kHz. 
The improvement in sound quality in- 
volves AM radios, which will be built 
with a "wideband" function that will 
receive the entire 10-kHz audio sig- 
nal. As mentioned in the article, AM 
broadcasts will be pre-emphasized 
and "wideband" AM radios will have 
a corresponding de-emphasis curve, 
reducing noise while keeping audio 
response flat out to 10 kHz, Although 
not quite the equal of FM radios 15- 
kHz audio response, wideband AM 
comes very close to matching FM's 
sound, and will dramatically improve 
the public's enjoyment of music 
broadcasts on AM radio. 

Although I am only 16 years old, I 
have devoted much time to the study 
of radio, especially AM radio. 
MATTHEW BAILEY 
Stone Mountain. GA 



A VOICE OF EXPERIENCE 
Radio-Electronics certainly fills 
a gap in the information world, not 
only for the novice who is anxiously 
pursuing the fascinating and useful 
study of electronics, but also for 
keeping more experienced readers 
posted. In addition, the magazine pro- 
vides recreation in the form of con- 
struction projects, featuring unique 
and useful devices for us to build. 
I have a suggestion to offer regard- 
ed ing the excellent series called "Intro- 
z duction to Microwave Technology" 
§ by Joseph J. Cam In the September 
o issue, on page 69, it states that the 
y three traditional methods for generat- 
jij ing RF energy were spark gaps, Alex- 
5 anderson alternators, and vacuum 
cc tubes. It appears that arc generators 



were omitted from that category, al- 
though they were commonly found on 
board ships where the principle 
power source was 115 VDC. The arc 
signals were characterized by a much 
smoother wave band than spark sets, 
and were preferred by ship operators. 
They also were much more efficient 
than spark sets. (A sketch of such a 
device appears in Fig. 1.) 



-V<V 



R1 L1 



+115VDC 



SPARK 
GAP 




FIG. 1— THIS CIRCUIT SHOWS an arc-gen- 
erator, which was used on-board ships 
where the primary power source was 115 
volts DC. 

Also on page 69 is a reference to 
using a Ford Model A ignition coil for 
a spark source of power. That is ap- 
parently an oversight, since the coils 
in demand were the vibrator-driven, 
type that were found on the Ford 
Model T. 

FRANK J. BURRIS 
Fallbrook. CA 

BUILD A RESISTANCE STANDARD 

A "standard resistance" value is a 
necessity for a calibration laboratory. 
However, those certified standards 
can represent a sizable investment. If 
you are performing calibration ser- 
vices in the field as a secondary func- 
tion, buying a "standard" can be 
difficult to justify. However, there is a 
way in which a "resistance standard" 
can be designed, fabricated, and cer- 
tified for a nominal sum. 

First, select the value of resistance 
that you need most, and then obtain a 
precision resistor of that value. That 
resistor should be a 1 %-or-better tol- 
erance component. Verify the true 
resistance of the device on a certified 
instrument that is at least ten times 
the accuracy of the resistor. That 
reading, taken between 72°F and 
78°F, becomes the "certified value." 

For example, I made a 1.62-kilohm 
resistor standard. I used a Dale 50- 
watt. 1%, wire-wound resistor as a 
"standard" value, and verified its true 
value with a 4'/2-digit DMM certified 
to have a 0.1 % ± 2 LSD (least signifi- 
cant digit) error factor on the 0-2- 
kilohm range. The test leads were 
"zeroed" to eliminate their resis- 



tance from influencing the readings. 
The ambient temperature on the sur- 
face of the component was verified to 
be 75°F I made a series of 1 individu- 
al resistance measurements at 10- 
minute intervals, which prevented the 
component's value from changing 
due to internal heating caused by cur- 
rent from the measuring instrument 
flowing through the resistor. That 
change could be 1-2 ohms in a less 
expensive resistor but. since we are 
building a "certified standard," the 
marked value should be as accurate 
as possible. The ten readings were 
identical: The resistor proved to have 
an value of 1617 ohms. That is within 
the 1% tolerance specified. 

The value derived by the use of the 
precision ohmrneter is the "true" or 
"certified" resistance of the compo- 
nent. The "nominal" value is 1620 
ohms. Now that the numerical values 
have been established, we can pack- 
age the unit. 

Because it is a "traveling stan- 
dard" we cannot always control the 
environment in which it will be used. 
We must provide a thermal mass to 
surround the resistor, and thereby act 
as a temperature stabilizer Encasing 
the resistor in a thermal insulating 
compound prevents a sudden 
change of environmental tempera- 
ture from affecting the measured val- 
ue of the resistor. 

I soldered two #16 insulated leads 
soldered to the resistor, and lowered 
it into a mold cavity Can empty Spam 
can sprayed with mold release). I 
placed the resistor in the center of 
the cavity and used a casting resin to 
fill the mold. The resin took two hours 
to set and 24 hours to cure. 

Once the casting was removed 
form the mold, I repeated the initial 
resistance readings to ensure that 
the value of the resistor had remained 
constant. After performing the sec- 
ond resistance verification, I drilled 
two mounting holes through the cast- 
ing. I bolted the casting into a small 
cabinet and sealed the enclosure 
with rivets. My new traveling resis- 
tance "standard" is marked: 

"RESISTANCE STANDARD." 

"NOMINAL VALUE— 1.62K @ 
1%" 

"CERTIFIED VALUE— 1,617 
OHMS @ .185%" 

"(Certified in thermal isolation 
mass at 75°R" 
CHARLES H. STURKEY 
Newhail, CT 



22 




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Micronta's Voice Meter Digital Muititester 



Using a digital multimeter isn't 
a difficult thing to do — or at 
least it shouldn't be. On a 
benchtop, that may be true. But in the 
real world of field measurements, 
using a multimeter can often try your 
patience — and your balance. Some 
of us have not-too-fond memories of 
measurements made on top of a lad- 
der or catwalk, with half of our bodies 
reaching for the test points and the 
other half simultaneously stretching 
toward the meter to read its display. 
Others can relate to making under- 
dash automotive measurements 
where it's difficult to get your head 
positioned to see where you put the 
multimeter probes, let alone see the 
display. 

Of course, multimeter manufac- 
turers are more than happy to find 
solutions to the problems that their 
users encounter. We've seen several 
techniques that are used to freeze 
the display and hold a reading of inter- 
est. While they work well, and are a 
perfect solution for many situations, 
they all share one feature that is a 
failing in other situations: You have to 
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reading. 

Radio Shack C700 One Tandy Cen- 
ter, Fort Worth Texas 76102, and 
more than 7000 locations nation- 
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solution: their Micronta Voice Meter. 
At the push of a probe-mounted but- 
ton, the meter announces the mea- 
surement in a clear voice. 

The Voice Meter doesn't look 
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ital multimeters. Its gray plastic case 
measures roughly 7 X 3 x 1 % inches, 
and features a 3%-digit (3000-count) 
LCD readout, a power switch, and a 
six-position rotary function-selector. 
The six measurement functions are: 
DC volts, AC volts, diode check, re- 
sistance, DC current, and AC cur- 
rent, 

DC and AC voltages are measured 
in five and four ranges respectively: 
3000 volts with a resolution of 1 volt; 
300 volts with a resolution of 0.1 volt; 
30 volts with a resolution of 0,01 volt; 



Here's a look at <i 

digital multimeter 

that speaks 




CIRCLE 10 ON FREE INFORMATION CARD 



3 volts with a resolution of .001 volt; 
and (for DC only) 300 millivolts with a 
resolution of 0.1 mV. 

Resistance is measured over six 
ranges, from 300 ohms through 30 
megohms, with resolutions that 
range from 0.1 ohms in the 300-ohm 
range to 10K in the 30-megohm 
range. DC and AC current are mea- 
sured in a single range of 300 milli- 
amps, with a resolution of 0.1 
milliamp. 

Using the Voice Meter isn't signifi- 
cantly different from using standers 
multimeters. In fact, you don't have to 
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not to. If you do choose the voice 
feature, getting the meter to speak is 
as simple as pressing a button on the 
positive probe. Unfortunately, if you 
need the voice capability, you must 
use the probe supplied with the 
meter. 

While we initially found the voice to 
be a novelty, it quickly got on our 
nerves when we made repeated 
measurements. Despite the Voice 
Meter's clear, slow, easy-to-under- 
stand voice, we preferred simply 
glancing at the meter when making 
most measurements because it was 



faster and quieter. CNo volume con- 
trol is provided on the meter). How- 
ever, for our tests where we couldn't 
see the meter's face, the voice, of 
course, proved invaluable. 

The Voice Meter is powered by 
four "AA" batteries. When the bat- 
teries are low, a batt annunciator 
makes you aware of the fact. If you 
don't notice it. you will be prompted 
by an insistent "Replace batteries" 
announcement when you try to get a 
voice reading. 

Our overall impression of Radio 
Shack's talking multitester was favor- 
able. The only feature we didn't like 
was that the test probes don't offer 
sheathed banana plugs — an impor- 
tant safety consideration when 
you're making high-voltage measure- 
ments. 

Although we liked the meter, we 
doubt it will find favor in professional 
circles. Most professional users — 
except those who really need voice 
capability — will want more features, 
ruggedness, and higher accuracy. 
However, most of those profession- 
als will find the $99.95 Voice Meter a 
perfect addition to their home work- 
bench. R-E 



24 



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PORTABLE REAL-TIME 
OSCILLOSCOPE. The 

model 2252 programmable 
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cilloscope from Tektronix 
provides the precision, ver- 
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an analog scope, plus the 
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A unique sequential- 
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All oscilloscope func- 
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CIRCLE 16 ON FREE INFORMATION CARD 



and measurement con- 
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The 2252 real-time os- 
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SOLDER-MASK REPAIR 
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while it protects against 
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The overcoating is safe for 
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AUTORANGING DIG- 
ITAL MULTIMETER. De- 
signed for convenient test- 
ing and troubleshooting, 
B&K-Precision's model 
2701 autoranging DMM 
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clips built into its case for 
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storage of probes. The 
compact, hand-held multi- 
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used to test AC and DC 
voltage and current, as well 



26 




CIRCLE 18 ON FREE 
INFORMATION CARD 

as for resistance, diode, 
and continuity checks. The 
2701 has a 3'/ 2 -digit LCD. 
Its functions include auto- 
ranging, "High" and "Low" 
power ohms, and data 
hold. A 9-volt battery pro- 
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The 2701 autoranging 
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sion, Maxtec International 
Corp.. 6470 West Cortland 
Street, Chicago, IL 60635: 
Tel: 312-889-1448. 



FREON-GAS ANTI- 
DUST SPRAY. Containing 
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foreign particles from deli- 
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12-ounce can delivers a 
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freon gas precisely where it 
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Dust-A-Way freon gas 




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spray costs $7.95 for a 1 2- 
ounce can —Jensen 
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RACK-MOUNT LINE 
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CIRCLE 20 ON FREE 
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ages. Built-in surge sup- 
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The LCR-2400 rack- 
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LOGIC ANALYZERS. 

Philips PM3580/PM 3585 
family of logic analyzers 
feature quick set-up time — 
users need less than 30 
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up menus and VGA graph- 
ics offer a simple interface 
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short cuts for quick opera- 
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tained by reducing state 
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fully-integrated state and 
timing triggering. All mea- 
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resolution. 




CIRCLE 21 ON FREE 
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The logic analyzers fea- 
ture a unique dual-analyzer- 
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Other features include a 
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connectors for easy trigger 
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DIGITAL SIGNAL PRO- 
CESSING BOARD. 

Daianco Spry's model 250 
digital signal processing 
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bus-compatible microcom- 
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DSR and can accommodate 
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populated with up to 64K 
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128 words of one-wait- 
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available to both the PC 



CIRCLE 55 ON FREE INFORMATION CARD 




CIRCLE 22 ON FREE 

INFORMATION CARD 

and the TMS320 DSP 
through the use of an on- 
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The model 250 features 
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model 250 includes as- 
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signal and spectrum dis- 
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record and playback to and 
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The model 250 digital 
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priced starting at $1095 
(40-MHz TMS320C25, 4K 
words of program RAM, 
and 32K words of data 
RAM). — Daianco Spry, 
89 Westland Avenue, 
Rochester, NY 14618; Tel: 
716-473-3610. 

HANDSHAKING MO- 
DEM. Offering full-duplex 
data transmission at rates 
of upto19.2kilobandanda 
bi-directional control sig- 
nal — all over two twisted 
pairs — Teiebyte Tech- 
nology's model 204 Hand- 
shaking Modem can pro- 
vide a "hardware hand- 
shake" for devices such as 
laser printers and various 
terminals. 

The "handshake" is typ- 
ically used when terminals 
are connected to a PBX 
switch, which uses the 
handshake to determine if 
the terminal is active or if 
its power has been turned 




CIRCLE 23 ON FREE 
INFORMATION CARD 

off. Housed in a small plas- 
tic case, the full-duplex 
modem measures only 2 x 
2%x 3/4-inches. 

The model 204 samples 
clear-to-send (pin 4), re- 
quest-to-send (pin 5). and 
transmit data of the 
RS-232 serial interface, 
and derives its operating 
power from them — no bat- 
tery or external power sup- 
ply is required. The stan- 
dard-data I/O occurs on 
pins 2 and 3 of the RS-232 
connector. The control sig- 
nal uses DTR (data termi- 
nal ready) as the hand- 
shake input and DCD (data 
carrier detect) as the hand- 



shake output. The input 
and output are switchable, 
to accommodate connec- 
tion of the modem to either 
a DTE or DCE device. The 
control signal input also 
controls the data flow from 
the modem. Data can be 
transmitted when the con- 
trol signal is high. The 
modem requires no sepa- 
rate power inputs. 

Data transmission be- 
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ferential baseband signal- 
ing techniques, and com- 
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capability is greater than 20 
volts. Those features are 
there to allow error-free op- 
eration in all kinds of noisy 
environments. 

The model 204 costs 
$89.00 in unit quantity and 
$68.00 in quantities of 100.— 
Teiebyte Technology 
Inc., 270 East Pulaski Road, 
Greenlawn, NY 11740; Tel: 
1-800-835-3298 or 516- 
423-3232; Fax: 516- 
385-8184. R-E 



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CIRCLE 86 ON FREE INFORMATION CARD 



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ELECTROMECHANI- 
CAL DESIGN HAND- 
BOOK; by Ronald A. 
Walsh. TPR, Division of 
TAB Books Inc., Blue 
Ridge Summit, PA 
17294-0850; Tel. 1-800- 
233-1128; hardcover; 
$49.50. 

The fields of electrical 
and mechanical engineer- 
ing are closely linked in the 
design and development of 
today's manufactured 
products. This book fills an 
important gap in the librar- 
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signers whose work re- 
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boundaries between elec- 
trical and mechanical de- 
sign. Including information 
about both disciplines, this 
well-organized book pro- 
vides practical product-de- 
sign data, working pro- 
cedures, and formulas in 
one comprehensive vol- 
ume. The broad range of 
subject matter covered in- 
cludes the following: spring 
design; standard fasteners 
and bonding methods; pro- 
totype construction; prod- 
uct liability, testing, and 
patents; basic pneumatic, 
hydraulic, air-handling, and 
heat equations and their 
uses; sheet-metal design 
and layout; and the selec- 
tion of bearings and gears. 
In-depth treatments of fre- 
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including descriptive ge- 
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circuit design, electronic 
components, fabrication 
techniques, drives, and 
linkages and mechanisms. 
The book provides real- 
world examples and more 
than 500 detailed illustra- 
tions. The emphasis 
throughout the pages of 




CIRCLE 11) ON FREE 
INFORMATION CARD 

this handbook is on the 
practical design data 
needed in the day-to-day 
development of parts, 
mechanisms, and assem- 
blies. 

'90/'91 CATALOG; from 
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Street, Dayton, OH 
45402; Tel: 513-222- 
0173; Fax: 513-222-4644; 
free. 

Packed full of electronic 
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wire and cable; TV, CATV, 
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tools; chemicals; switches; 
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Parts Express catalog.) 

MONITOR POCKET 
GUIDE; from Display 
Technologies, Inc., 1355 
Holmes Road, Elgin, IL 
60123; Tel. 708-931-2100; 
Fax: 708-931-2120; free. 
This 4 x 9-inch brochure 
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color monitors and mono- 
chrome models that range 
in size from 5 to 21 inches. 
The guide includes easy-to- 
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that list specifications such 
as CRT size, video and 
power inputs, horizontal 




CIRCLE 11 ON FREE 

INFORMATION CARD 



CIRCLE 12 ON FREE 
INFORMATION CARD 

and vertical frequencies, 
and bandwidth, for each of 
Display Technology's prod- 
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drawings of the products 
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cards. Highlighted in the 
brochure are the Color 
Pix.L monitors, which fea- 
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technology. In addition, the 
pocket guide contains a 
listing of sales offices and 
guidelines for choosing a 
monitor supplier. 



BROADCAST DATA 
SYSTEMS: TELETEXT 
AND RDS; by Peter L. 
Mothersole and Norman 
W. White. Butterworths, 
80 Montvale Avenue, 
Stoneham, MA 02180; 
Tel: 617-438-8464; hard- 
cover; $39.95. 

Data transmission over 
TV and radio channels — 
commonly called teletext 




CIRCLE 13 ON FREE 
INFORMATION CARD 

and Radio Data System 
CRDS). respectively — are 
becoming important as- 
pects of modern broad- 
casting technology. This 
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practices and the comput- 
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in the teletext and RDS 
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development of teletext is 
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data-signal format and cod- 
ing methods used. The 
various components re- 
quired to form a complete 
system are described. 
Other chapters cover such 
subjects as preparing and 
recording subtitles, the 
networking of teletext data 
signals and regional ser- 



30 



vice requirements, teletext 
decoders, and the re-trans- 
mission of decoded tele- 
text signals as a video 
signal. The measuring 
techniques required to 
maintain broadcast net- 
works and to test decoders 
for both teletext reception 
and data distribution are 
described. The recent de- 
velopment of RDS, which 
allows digital data to be 
combined with a VHF radio 
signal, is discussed. The 
necessary techniques for 
both coding and decoding 
the signal are explained, 
and various applications 
are detailed — including the 
use of RDS to provide a 
local traffic-information ser- 
vice by interrupting net- 
work programming. 



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QUALITY OSCILLO- 
SCOPE PROBES; from 
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salem, PA 19020; Tel: 
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A variety of monolithic 
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specifications, and a handy 
cross-reference chart is in- 
cluded. Also highlighted in 
the catalog are a wide vari- 
ety of probe accessories, 
and a 40-piece connector/ 
adapter kit. 




GLOSSBRENNER'S 
COMPLETE HARD DISK 
HANDBOOK; by Alfred 
Glossbrenner and Nick 
Anis. Dvorak Osborne 
McGraw-Hill, 2600 Tenth 
Street, Berkeley, CA 
94710; softcover with 
diskettes; $39.95. 

This encyclopedic vol- 
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presented information on 
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puter users of all levels of 
expertise. The book in- 
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convenient tips about se- 
lecting, buying, and install- 
ing a hard disk; loading and 
organizing the hard disk for 



j@F r 1TV0KAKSSSSS™ 


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Gtossbrcnner's 
Complete 

HARD DISK 
HANDBOOK 




31 





CIRCLE 14 ON FREE 
INFORMATION CARD 



CIRCLE 15 ON FREE 
INFORMATION CARD 

maximum efficiency; res- 
toration and recovery tech- 
niques; networking; and 
special formatting pro- 
cedures. The first section 
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disk drives. The ins and 
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ery. Included with the book 
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torials, software tools, and 
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CIRCLE 78 ON FREE INFORMATION CARD 



THE INTERSIL ICM7216 

frequency- counter IC's 
(models A-D) have an 
impressive array of 
functions. All have a 
high-frequency os- 
cillator, decade time- 
base counter, 8-decade 
data counter and 
latches, 7-segment de- 
coder, digit multiplex- 
ers, and 8-digit multi- 
plexed LED-display 
drivers. 

There are four mod- 
els; the 7216A and 
721 6B are universal 
counters, capable of 
measuring input fre- 
quency, oscillator fre- 
quency, frequency 
ratio, period, and time 
interval, and can per- 
form unit counting. 
The frequency counter 
discussed here uses 
the 7216C with a com- 
mon-anode display (the 7216D is 
similar). It'll become one of the 
most versatile pieces of test 
equipment on your bench, and 
simply fun to use. You can build 
it for about $80. 

Circuit description 

Figure 1 shows the pinouts for 
all four 7216 versions: the 7216A/ 
B use two inputs for measure- 
ments like the ratio of two fre- 



BU1U) THIS 
BENCHTOP 

FREQUENCY 
COUNTER 



Add frequency-measurement 
capabilities to your workbench 
with this inexpensive counter. 



CARL BERGQUIST 

quencies. The 7216C/D use 
single inputs, but have external 
decimal point (exdp input) inputs 
(pin 13), and measurement in 
progress outputs (pin 2). 

The frequency counter sche- 
matic is shown in Fig. 2. IC2 de- 
cade counts the input frequency, 
stores the result in latches, driv- 
es an 8-digit multiplexed LED 
display, and blanks all leading 
zeros. While the internal os- 



cillator normally uses 
10-MHz crystal XTAL1. 
an external source can 
go on J3 to pin 24 of 
IC3 (ext osc input). 
Some other 7216C fea- 
tures are display 
blanking, measure- 
ment holding, and dis- 
play test- reset. 

Since IC2 is de- 
signed for a maximum 
reading of 10 MH2,IC1. 
a 7490 decade counter, 
expands the range to 
100 MHz by con- 
necting pin 1 (Bi N ) to 
pin 12 (Q A ) for the 
maximum count 
period. Pin 8 (Q c ) is 
tied to pin 28 (input a) 
of IC2 for measure- 
ment. For more expan- 
sion, IC3, a CD4017 
decade counter, is an 
adjustable divide-by- 
N. 
As mentioned earlier, there are 
four ranges, and operation is 
possible with or without IC3. 
When S8 is set to out, IC3 isn't 
used, and the display reads 1:1, 
showing the actual undivided 
frequency of the input on Jl or J2 
in kHz. Obviously, if the frequen- 
cy of the input goes below the 
nominal minimum possible for 
any given range, the display will 
read zero. 







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CONTROL INPUT INPUT A 

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FUNCTION INPUT OSC OUTPUT 

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SEG i | EXT OSC INPUT 

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OSC INPUT 

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OUTPUT^ DIGIT 3 
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15 



FIG. 1— THE PINOUTS OF ALL FOUR VERSIONS of the 7216. The 7216A/B both take two 
inputs, for measurements like the ratio of two frequencies, while the 7216C/D have single 
inputs. 



If the frequency counter had ad- 
equate bandwidth, it could actu- 
ally read from 1 kHz-99.999,999 
kHz without IC3, or 1 kHz- 
99.999999 GHz. Of course the 
frequency response isn't nearly 
that good, and the counter actu- 
ally works up to only about 1.8 
GHz (using IC3). regardless of S6 
orS7. 

With S6 set to 0.1 second with 
IC3 out, the counter displays 0. 1 
kHz-9,999,999.9 kHz, or 100 
Hz-9. 9999999 GHz. Setting $6 
to 1 second, it displays 0.01 
kHz-999,999.99 kHz, or 10 
Hz-999. 99999 MHz. And, set- 
ting S6 to 10 seconds, it displays 
0.001 kHz-99.999.999 kHz, or 1 
Hz-99. 999999 MHz. 

If S8 is set to in, IC3 is on, and 
the display reading has to be 
multiplied by the divider factor 
setting of S7 to get the actual fre- 



quency. The maximum divider 
ratio of 18 may seem like an odd 
value to end with, but IC3 didn't 
have enough taps to divide by 20. 
Never use an input exceeding 
V UD ; you'll destroy IC2. Reduce 
the input gain with R7 and in- 
crease for a stable reading. 

Regarding DSP1-DSP4, the 
MAN6710 2-digit, 7-segment 
LED displays, the digit drivers 
are in order along the boLuim, 
with the view from the fror; : ''in 
14 is the digit driver for th left- 
hand digit, and pin 13 is fo the 
right-hand digit. The left-hand 
digit in DSP4 has the segments 
and decimal point labeled for ref- 
erence. The segment driver pins 
go on the left side in pairs; the 
former in each pair is a left-hand 
segment, the latter a right-hand 
segment. Thus, for example, pin 
16 is A L , and pin 1 1 is A R . 



PARTS LIST 

All resistors are Vi-watt. 5%, unless 
otherwise noted. 

R1— 3300 ohms 

R2— 100.000 ohms 

R3, R5— 10.000 ohms 

R4 — 22 megohms 

R6— 22,000 ohms 

R7 — 500,000-ohm front panel potentiom- 
eter 

R8— 470 ohms 

R9 — 1 -megohm PC- board potentiometer 

R1 0—1000 ohms 

Capacitors 

C1 — 100 pF, ceramic disc 

C2— 27 pF, ceramic disc 

C3— 6-50-pF PC-board trimmer 

C4, C8 — 0,1 )j.F, ceramic disc 

C5— 3300 jj-F, 25-volt electrolytic 

C6— 1 plF, 10-volt electrolytic 

C7— 100 pF-1 jj.F PC-board trimmer 

Semiconductors 

D1-D4— 1N914 diode 

BR1 — 1.5-amp bridge rectifier 

DSP1-DSP4— MAN6710, 2-digit, red, 
common-anode, 0.506-inch. 7-seg- 
ment LED displays 

IC1— 7490 BCD counter 

iC2— Harris 7216C frequency counter 
(Digi-Key ICM7216CIJt) 

IC3—CD401 7 decade counter 

IC4— 7805 S-vofl DC regulator 

IC5 — 555 timer 

LED1 — miniature red T-1 light-emitting di- 
ode 

LED2 — standard green, jumbo, diffused. 
T-1- 3 /o light-emitting diode 

Switches 

Si, S5— SPST momentary push button 

S2-S4— SPST ON/OFF push button 

S6 — SP4T rotary switch 

S7— SP9T rotary switch 

SS— DPDT toggle switch 

S9— SPST ON/OFF- push button 

Other components 

J1.J2— RCA jack 

T1— 120-to-l2.6-volt. 1.2-amp, AC power 
transformer 

F1 — 1 ,5-amp fuse with holder 

PL1— 120-vott AC power cord 

XTAL1— 10-MHz crystal 

Miscellaneous: Plastic cabinet (mini- 
mum size 8x6.25x3-inches, 7805 
heat sink, bezel for LED2, 5-pin cab- 
inet-mounted terminal strip, knobs, dry 
transfer lettering, hardware, solder, 
wire, etc. 

NOTE: The MAN6710's are available 
from Quality Technologies Corp., 
3400 Hillview Ave., Palo Alto, CA 
94304, (415) 493-0400 or (800) 
533-6786. The 7216C is available 
from Digi-Key Corp., 701 S. Brooks 
Ave., P.O. Box 677, Thief River Falls, 
MN 56701-0677, (218) 681-6674 or 
(800) 344-4539. The cabinet is avail- 
able for S14.95, from Chaney Elec- 
tronics, 932 North 94th Way, Scot- 
tsdale, AZ 85258, or P.O. Box 4116, 
Scottsdale. AZ 85261, (602) 451-9407 
or (800) 227-7312. 



i +5V 



16 



S7 

FREQ. 

DIVISION 

KCTOR 




to 



IS 



R6 
22K 



13 



+5V 



OUT1 v fOOUT0 
OUT2 CLK 
OUT3 
0UT4 

OUT5 IC3 

OUT6 C04017 

OUT7 

0UT8 

0UT9 

RST V ss 

CLK ENABLE 



If SV 



TIN 



^L 



(LABELED 

■100MHz" 

ON PROTOTYPE) 

INPUT A 

J1© ! 

(LABELED 

"FREO-DIV." 

ON PROTOTYPE) 



<"R7 



BOOK 
INPUT 
GAIN 



ss^-i 

FREQ 
pDIVO 
OUT 



R1 

3.3K 



,+5V 



14 



12 



A, H V DD Q, 

IC1 R 
T49D n 

B K 

rig, 

Q».. D 



J2 

- (UNUSED) 



1 



27pF 



EXT 

OSC 

INPUT 

J3®- 



++5V 



18 



M 



C3 
6-50pF 



•XTAL1 
i^lOMHi 

R4 ■ 
22MEG' 



25 



2e 



S1 

;hold 



r R2 1: 

10OK" 2 



23 



•iT 



S5 

RESET 



O O-i 



12 



R3 
10K 



H 



*loS4 

DISPLAY 

TEST 

D1 

1N914 



10OpFX 



RS 
10K 

EXT 

DEC PT 



J 



oS3 
DISPLAY 
BLANK 
DZ 



l LED1 
'(RED) 



H 



gSZ 
EXT 
OSC 

A 03 $ 



1N914 L1K914 



+& 



H 



7 



OSC 
INPUT 



IC2 
ICM7216 



A. 

B 
C 
D 

E 

F 

G 

DECPT 

OUT 

DIGO 

D1G1 

DIG2 

CNTRL INPUT D | G3 
EXT DEC 
PT IMP DIG4 

RANGE 

INPUT 

DIGS 

DIG7 



OSC 
OUT 

HOLD 
INPUT 
INPUT A 

RST 

INPUT 



DIGS 



10 



11 



23 



22 



21 



2D 



19 



17 



16 



15 



S6„ SAMPLE 



D4 
1H914 



01 



~P = ° TIME 

9 Vm 

I - 1 ? T 1 _ 



iy 



14 DSP4 13 



I4 



DSP3 



13 



14 



III 



DSP2 



13 



1-1 



DSP1 



13 



f B 

G 



E C 

D 



DP 



G L .S, 



E L -E B 

Mi 
c L ,c, 

B L ,B, 
A L .A, 



4,9 



17,7 



18,12 



us 



2,6 



3,8 



15,10 



16,11 



PL1 
120VAC 




5VDC 



FIG. 2— THE FREQUENCY COUNTER SCHEMATIC; IC2, the 721 6C, counts input frequen- 
cy in decades, stores the result in latches, and drives an 8-digit multiplexed LED display, 
with leading zero blanking. While the internal oscillator normally uses with 10-MHz crystal 
XTAL1. J3 takes an external source. Other 721 6C features include display blanking, 
measurement holding, and display test/reset. 



Construction 

The parts-placement diagram 
for the main PC board is shown 
in Fig. 3, and the display board is 
shown in Fig. 4; the foil patterns 
are also provided in this article. 
The prototype version omitted 
the power supply now incorpo- 



rated in the main PC board. Use 
18-pin DIP sockets for the LED- 
display PC board, and appropri- 
ate sockets for the main PC 
board. The wire groups for both 
the segments and the digits are 
indicated in both Figs. 3 and 4, 
and are omitted for clarity. 



The Monsanto MAN6710s are 
2-digit, 7-segment, multiplexed, 
common-anode LED displays; 
their pinouts are shown in Fig. 5. 
The B, D, F, and DP segments 
were connected by PC-board 
foils, and the A, C, E. and G seg- 
ments using jumpers; the G jum- 
pers criss-cross the display PC 
board as they progress. Use 
multi-colored wire to identify the 
various segments and digits; dig- 
it drivers D1-D8 go to the top of 



o 

m 
O 



DO 
m 
30 

CD 

CO 

o 



35 



Ch TO SEGMENT 




FIG. 3— THE PARTS PLACEMENT DIAGRAM lor the main PC board. Use sockets for the 
ICs. The wire groups for both segments and digits are shown. 



7o- 
60- 



50- 



DIGIT > 4 o- 
DRIVERS^ 3 O- 



TO 

SEGMENT 

DRIVERS< 

ON FCZ 



fAO— M 

fe\ DISP1 1 ' It 



1 r 

DISP2 







j 1 j 1 




^ (3) 



FIG. 4— THE PARTS PLACEMENT DIAGRAM for the LED-display PC board. LED1 goes on 
the right end of the PC board as shown, with the cathode tacked to the foil itself (not a 
pad), and the wire groups for the segments and digits are shown. Most jumpers don't 
have separate foil pads, and are tacked onto pads used for other wires. 



LEFT DIGIT RIGHT DIGIT 

X X 

H 14 , . \™J- 

% t' MANB710 

®©($>®(f)©®(!)®(i) 

IIIIII 



®® 

*i 1 1 i 1 1 T 

■ni H 2 H 3 H 15 n 16 M 17 1-1 19 M 4 H 5 ti 6 M 7 t-t 8 '"< 10 H 11 J"f 12H 9^ 

*•-' ^_^ ^_' v • \ • * • ^ / ^—^ v,' vv v ^ \ / V V \ / v / \ s 




g 

z 
o 

EC 

I 

_l 
LU 

g 
c 
< 
rr 



7 
c 



7 T 



T 

G 



T 

DP 



"" 



T 

B 



1 



T 

DP 



FIG. 5— PINOUTS FOR THE MAN6710 2-DIGIT, 7-segment, common-anode, multiplexed 
LED display. 



the display board. Several jum- 
pers must be tack soldered to the 
pads on the foil side of the display 
board. 



The reason Jl and J 2 are con- 
nected together is because in the 
prototype, the original plan (later 
abandoned) was to make a uni- 



versal counter, needing two in- 
puts to make full use of available 
IC functions. The parts dis- 
tributor the 7216C was obtained 
from thought version C was a 
universal counter. By the time 
the mistake was discovered, the 
front-panel holes on the cabinet 
had already been drilled. To avoid 
an empty panel hole, dummy 
RCA jack J2 was placed there, in 
parallel with Jl. 

Although Fig. 2 indicates that 
Jl is the one that's actually used 
rather than J2. either was usa- 
ble, but only one at a time. Ob- 
viously, you wouldn't need both 
jacks on yours, and should only 
drill one panel hole. The inputs 
on Jl and J2 were to have been 
"100 MHz" and "FREQ DIV," 
purely arbitrary titles stemming 
from personal preference. In the 
originally planned version, two 
7490 decade counters were to 
have been used, one for each in- 
put. The finished frequency 
counter is shown in Fig. 6. 

Figure 7 shows an overhead 
view with the top open. A 470- 
ohm resistor was installed for 
R8, slightly above the center on 
the left side of the main PC board, 
but never used in the prototype. 
Instead, another 470-ohm re- 
sistor was placed off-board, in se- 
ries with LED2, behind where 
LED2 and its bezel fit into the 
front panel. The prototype really 
used four boards, but only the 
main and display boards had 
foils. 

The IC4 heatsink is of sheet 
aluminum, bent to fit in the cab- 
inet, with silicone grease used for 
good heat transfer, and C6 under- 
neath. In the prototype, 24-pin 
DIP sockets were used. The right- 
most piece was cut from a whole 
one, and has only six pins. Since 
the three sockets and the cut 
piece at right fit flush against one 
another, there's an unused hole 
between individual displays. To 
avoid cutting a socket, use 18-pin 
versions in yours. The 5-pin ter- 
minal strip is used as a feed point 
for the +5 volts from IC4. 

Figure 8 shows a closeup view 
of the LED-display PC board from 
the foil side. Since three holes 
were needlessly drilled for Jl— J3. 
there wasn't enough room left for 
S8, so a notch was cut in the 
lower left corner of the display PC 
board, clearly visible in Fig. 8. 
The wires to LED1 are at upper 



36 




J1 J2 

(SEE TEXT) 



FIG. 6— THE FINISHED FREQUENCY COUNTER, shown in display-test mode, with all 
digits and decimal points lit. J1 and J2 are wired together, but one is unnecessary (see 
text). 



DSPt 



DSP4 R7 



87 

R8 

(WRAPPED 1 

IN TAPE) 

IC3 

IC1 
RS(UNUSED) 



8 I S2 S4 S3 S1 S5 / S9 I 




se 



D1 

02 (CATHODES 

■ D3 AT RIGHT) 

■ D4 



T1 CENTER 
TAP(UNUSED) 



TERMINAL 
STRIP 



C6 |C4 
(UNDER C5 

HEAT SINK) 

FIG. 7— AN OVERHEAD VIEW OF THE PROTOTYPE; R8 on the main PC board wasn't 
used. Another off-board 470-ohrn resistor is in series with LED2, and 1C3 and IC4 were 
later added to the main PC board. The IC4 heatsink is sheet aluminum with silicone 
grease; C6 is underneath. The prototype had three complete 24-pin DIP sockets for the 
LED displays, and part of another, with an unused hole between displays; use 18-pin 
sockets in yours. The markings shown on D2 and D4 are wrong; the cathodes all point 
right. The terminal strip is a feed point for the + 5 volts from IC4. 



right; normal polarity is re- 
versed, with black going to the 
anode, and white to the cathode. 
Note the unused pads between 
individual LED displays, where 
they fit against one another on 
the component side. 

The prototype cabinet is 8 
X6.25 x3-inches; drill the front 
panel holes, and do the labeling 
before installing the switches, 
jacks, and display. Use dry trans- 
fer lettering with a light coat of 
clear enamel to prevent damage. 
The prototype has the labels of 
the digit drivers used on S6 for 
setting the display decimal point; 



instead, use the sample times 
shown in Fig. 2. Mount Tl, an- 
chor the PC boards, and check 
for wiring errors. 

Power-up, test, and calibration 

When you apply power, LED2 
should glow. Press S4 (display 
test), and the display should 
show all 8s and decimal points, 
and LED1 should light. If not, 
disconnect the power and re- 
check the wiring. With S8 in the 
out position, IC1 is off; set R7 for 
maximum gain, and apply a sig- 
nal of known frequency no more 
than 5 volts in magnitude to Jl or 



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CIRCLE 19B ON FREE INFORMATION CARD 37 



TABLE 1— IDEAL FREQUENCY COUNTER DISPLAY RANGES FOR ALL S6/S7 SETTINGS 



Frequency 
Divider 
Setting (S7) 

Sample Time 
Setting (S6), s 


1 


2 


4 


6 


8 


0.01 


1-99,9999.999 


2-199,999,998 


4-399,999,996 


6-599,999,994 


8-799.999,992 


0.1 


0,1-9.999,999.9 


0.2-19,999,999.8 


0.4-39,999.999.6 


0.6-59,999,999.4 


0.8-79,999,999.2 


1.0 


0.01-999.999.99 


0.02-1.999,999.98 


0.04-3.999,999.96 


0.06-5.999,999.94 


0.08-7.999,999.92 


10.0 


0.001-99.999.999 


0,002-199,999,998 


0.004-399,999.996 


0.006-599,999.994 


0.008-799,999.992 



Frequency 
Divider 

Setting (S7) 

Sample Time 
Setting (S6), s 


10 


12 


14 


16 


18 


0,01 


10-999,999.990 


12-1,199,999,988 


14-399,999,986 


16-1,599,999,984 


18-1.799.999,982 


0,1 


1 .0-99,999,999.0 


1.2-119.999,998.8 


1.4-139,999,998.6 


1.6-159,999,998,4 


1.8-179,999,998.2 


1.0 


0.10-9.999,999.90 


0.12-11.999,999.88 


0.14-13,999,999.86 


0.16-15,999,999.84 


0.18-17.999,999,82 


10.0 


0.010-999,999.990 


0.012-1,199,999.988 


0.014-1.399,999.986 


0.016-1.599.999.984 


0.018-1.799,999.982 



Note: The actual frequency response is limited to approximately 1.8 GHz for all S6/S7 settings; all values shown here in kHz. 



DSP1 



DSP2 



DSPS 



DSP4 



en 
o 
z 
o 
cc 

§ 

uu 
_i 

o 

Q 
< 

cr 




FIG. 8— A CLOSEUP OF THE FOIL SIDE OF THE LED-display PC board. Most jumpers go 
directly to the foil-side pads; there are no separate holes. Since holes were drilled for 
J1-J3, there wasn't room for S8, so a notch was cut in the lower left corner. The wires to 
LED1 (beneath the PC board) are at upper right, black to anode, white to cathode. The 
pads between the displays are unused, where they fit against one another on the compo- 
nent side. 



J2 from a digital pulse generator. 
Tune C3 until the display- 
shows the same frequency as 
your standard, and the counter 
is calibrated. Switch S6 controls 
the number of digits of resolu- 
tion following the decimal point. 
The frequency is in kHz, so 1 kHz 
on the 10-second setting of S6 
should show up as 1.000. As you 
increase the sample time on S6, 
the accuracy increases but so 



does the measurement interval. 
On the 0.1-second setting, the 
reading is to one decimal place 
but takes only 0.1 second, where- 
as on 10.0-second setting, there 
should be three decimal places, 
but the sample time also in- 
creases accordingly. 

The setting on S7 is the factor 
an input frequency is divided by. 
Thus, a 100-MHz signal reads 50 
MHz on setting S7 to 2, 25 MHz 



OUTPUT 
(1.44Hz 
-7.21MHz) 

i 

+ 5V- * 



GN0 

TRIG 

OUT DISC 

IC5 

555 

THR 



^^1MEC 

7 



RST 



BYP 



R9 
MEG 



RIO 

M 



1.7 
100pF-1nF 



I 



C8 

0.1 



FIG. 9— AN OPTIONAL 555-TIMER ASTA- 
BLE square-wave generator for debug- 
ging the frequency counter. Both R9 and 
C7 are variable, to vary the output fre- 
quency from 1.44 Hz-7.21 MHz. The bread- 
board with this circuit on it appears in the 
lead photo. 

on setting S7 to 4, etc. Converse- 
ly, 100 MHz on the display on set- 
ting S7 to 10 implies a 1-GHz 
input. S5 resets the display to 
zero. SI retains a readout as long 
as needed, S3 just blanks the dis- 
play, S2 introduces clocking from 
an external source on J3, and 
LED1 indicates overflow. 

A simple astable multivibrator 
square-wave generator is shown in 
Fig. 9 for calibrating die frequency 
counter. Adjusting R9 and C7 will 
vary the output frequency from 
1.44 Hz-7.21 MHz. R-E 



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CIRCLE 186 ON FREE INFORMATION CARD 











CHRISTMAS 
CARD 








r/f/s electronic 
Christmas tree 
is sure to make 
anyone's 
Christmas 
a little brighter. 



RON HOLZWARTH 




HERE'S A PROJECT THAT YOU'LL BE 

happy to display in your front 
window this Christmas season- 
it also makes a great gift that any- 
one else would love to display in 
his or her window. The electronic 
Christmas tree is actually made 
from a printed circuit board with 
traces that form the branches of 
the tree. Different colored LED's 
mounted on the board simulate 
Christmas-tree lights. A built-in 
microphone picks up any audio 
signals — such as Christmas mu- 
sic—and different strings of 
LED's light according to the spec 
tral distribution of the audio 
within a frequency band selected 
by the constructor. When in- 
stalled in the custom metal 
frame, all of the electronics and 
the batteries are hidden behind 
the black mat and protected by 
the front glass. The end result is 
an attractive little Christmas tree 
whose lights will blink in unison 
with any kind of audio. 

The photographs cannot con- 
vey the effect of the flashing 
lights, nor the vivid impression 
of seeing sound. Music becomes 
a quickly moving pattern of danc- 
ing lights. In fact, any sound be- 
comes an Interesting display as 
the microphone, which tops the 
tree, picks up any sound in the 
room. For the hearing-impaired, 



l 


















it opens up a new window to 

sound. 

The project is also good for 
those who wish to learn about 
audio. For example, the tuning 
fork option only receives frequen- 
cies very near A440. Bui. it is 
hard to vocalize anything at any 
pitch without generating a dis- 
play. In fact, singing notes far 
lower than A440 generates vari- 
ous displays. In addition, inflec- 
tions, such as the rise in pitch 
that usually accompanies the 
conclusion or a question, are 
quite visible. 

The unit is powered from four 
AA batteries, although an AC 
adapter jack Is also included so 
that battery power can be con- 
served. It is a good idea to use an 
AC adapter whenever possible, as 
battery life is limited to about 
eight hours, depending on the 
volume level of the audio signal 
(more or less LED's will light), 
and the options selected. 

The strings of LED's can be 
more accurately thought of as bar 
graphs. The device includes an 
amplitude-discrimination cir- 
cuit that selects the harmonics of 
greatest amplitude and displays 
those harmonics in bar mode, at 
which time all others are in dot 
mode. 

An interesting experiment 
would be to interface the board 
with other circuitry. The outputs 
of the drivers are TTL- and 
CMOS-compatible. Since most 
LED posts can be wire-wrapped. 
wiring selected outputs to an in- 
put port is easy. The device can 
then function as a front end to 
allow your computer to monitor 
sound waves without (he com- 
plexity of digital filtering. The 
outputs can also be used to oper- 
ate relays, allowing lights of any 
power level to be used. 

Circuit operation 

Although the circuit may at 
first seem complicated, it really 
isn't. Figure 1 shows a block di- 
agram of the circuit. Signals 
from the microphone are ampli- 
fied, filtered, and automatically 
adjusted for gain in the automat- 
ic gain control (AGO section. The 
sections that follow are dupli- 
cated four t imes. All four sections 
are identical except for the fre- 
quencies that they handle. Each 
section has a level-adjust potenti- 



ometer, a bandpass filter, 
level shifter, demodulator 
and discriminator, and a 
display driver. Each dis- 
play driver drives a 
separate LED bar 
graph at the output. 
Three of the bar .-" 

graphs (A-C) con- 
tain ten individ- 
ual LED's. and 
one of them (D) 
contains twenty. 

Let's take a look 
at the schematic in 
Fig. 2, Power for the 
unit is supplied by the 4 AA 
batteries mounted on the 
board or supplied through the 
power jack ( J 1 ) on the back of the 
board. Since a bridge rectifier 
(consisting of diodes D1-D4) is 
used, DC of either polarity can be 
used, as well as AC. The batteries 
are disconnected whenever a 
plug is in the power jack. 

Two large electrolytic capaci- 
tors, C19 and C20. damp any 
transients caused by power sur- 
ges when a large number of LED's 
are lit. A voltage divider is formed 
by IC14, an LM336-2.5. which 
operates much like a Zener di- 
ode, but without nearly as much 
variation in reference voltage. 
The device has three terminals, 
and physically looks like a tran- 
sistor. However, the third termi- 
nal is not needed in this 
application, so the device is 
drawn in the schematic as a 
Zener diode. The reference volt- 
age from 1C14 is divided and then 
wired to op-amp ICl-c which is in 
a buffer configuration. The out- 
put of ICl-c (pin 8) then serves as 
an analog ground for later 
portions of the circuit. 

The output from the electret 
microphone (MIC1) appears as 
an AC waveform. It is amplified 
by ICl-b, which is configured as a 
non-inverting amplifier with an 
adjustable gain set by potentiom- 
eter R8. 

The next stage is a bandpass 
filter UCl-a), which selects the 
frequencies to be used by later 
portions of the circuit. Following 
the initial filter is Ihe AGC thai 
limits the signal when the output 
reaches approximately 1.1 volts 
peak-to-peak. The gain will in- 
crease slowly during periods of 
silence, reaching maximum sen- 
sitivity after approximately Ihree 








•**. 



seconds. 

The AGC section consists of 
op-amp ICl-d configured as a 
non-inverting amplifier. When 
the output of ICl-d Increases. Q2 
turns on and allows a small 
amount of current to flow into 
C4. That will raise the gate volt- 
age of Ql, effectively lowering the 
resistance of R12, thus decreas- 
ing the gain of the amplifier as a 
whole. In the rest of the discus- 
sion, only one filter (filter A which 
controls bargraph A) will be de- 
scribed, as the others are identi- 
cal except for a few resistor 
values. 

A level-adjust potentiometer 
(R17) is next, followed by a buffer 
(IC2-a). As the potentiometer set- 
ting is increased, the amplitude 
of the filter output increases, 
causing more LED's to light at t he 
output. 

The stage that follows is 
nothing more than a summing 
amplifier. The input signal is 
summed with a portion of the 
output from the filter that fol- 
lows. With a little positive feed- 
back from the filter output, the Q 
is increased. Within the feedback 
network is another filter which 
has a resistive divider attached to 
it that causes it to act as a unity- 
gain filter. 

The next section is the level 
shift, which is necessary since 
the output of the filter appears as 
an oscillation about the analog 
ground. The display drivers re- 
quire an input measured from 
true ground, hence the level shift 
section is needed to amplify the 



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output as well as lower the wave- 
form so that it is relative to 
ground. 

The output of the level-shift 
section, which is a series of half 
sine waves, goes through D7 to a 
resistor and capacitor in parallel 
(R61 and C14). Note that this is 
similar to a conventional AM de- 
modulator. The resistor values 
control the rate at which the dis- 
play falls back to a zero state. In- 
creasing the resistor values will 
make the display fall back (turn 
off) at a slower rate. 

The output of the demodulator 
goes to the amplitude discrimi- 
nator, which is an op-amp config- 
ured as a comparator. Ger- 
manium diode Dll will conduct 
whenever one of the filter outputs 
reaches 0.2 volts. Thus, C 18 will 
charge and remain at 0.2 volts 
below the highest DC level. That 
causes the comparator for the fil- 
ter output of the highest DC level 
to switch its output to a high 
state. That output connects to 
the control input of one section of 
a 4066 bilateral switch which 
connects power to pin 9 of the 
corresponding LED driver put- 
ting it in bar mode. 

Resistor R65 is of a much 
larger value than R61-R64. 
Thus, when the filter output be- 
gins to decrease, the driver re- 
turns to dot mode and does not 
go back to bar mode until the out- 
put increases. The time constant 
is set so that the voltage lias sig- 
nificantly decreased in about one 
second, so the rhythm of the mu- 
sic is displayed as the LED's shift 
to bar mode at each beat. Varying 
the RC time constant will make 
the device operate differently. 

Bargraph D is driven by two 
drivers (IC12 and IC13) stacked 
end-to-end. They are made to 
function exactly as the others as 
far as the dot-to-bar mode transi- 
tion is concerned. The display 
drivers (IC9-IC13) control the 
lighting of the LED's according to 
the input voltage. A databook 
should be consulted if you wish 
to know more about the opera- 
tion of the display drivers. 

Filters and Q 

The Q of a filter defines how 
narrow the passband is. It is 
equal to the center frequency di- 
vided by the difference in fre- 
quency between the -3-dB 
points. The -3-dB frequency is 



LEVEL 
ADJUST 

AND 
BUFFERS 



AM 
BANDMSS LEVEL DEMODULATION DISPLAY 

FILTERS SHIFT AND DRIVERS 

DISCRIMINATION 



LED 
BAR- 
GRAPHS 



J—] 



AGC 



INITIAL 

BANDPASS 

FILTER 




MIC 



CtV 



H^ 



-Wr- 



■w 



^ 



HC8rr4 



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■'■'.■»■ .--■:-:• ■ •>.-■.-. J .- 



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FIG. 1— BLOCK DIAGRAM OF THE CIRCUIT. Signals from the microphone are amplified, 
filtered, and automatically adjusted lor gain. 



the frequency at which the peak- 
to-peak voltage is attenuated by 
one half from that at the center 
frequency, assuming a constant 
voltage at the input. 

Assuming we want a center fre- 
quency of 440 Hz, which Is the 
American tuning standard for 
musical instruments, and we 
want A fiat (415.3 Hz), one half 
step down, to be a — 3-dB fre- 
quency, and A sharp (466.16 Hz), 
for the other -3-dB point, 440/ 
(466.16 -415.3) = 8.65. That would 
be the Q required for an attenua- 
tion of one half when stepping up 
or down one key on a piano. 

Interestingly enough, the same 
Q is required to accomplish that 
across the entire keyboard. This 
is a necessary consequence of 
our tuning scale, which is now 
defined as the twelfth root of two 
multiplied repeatedly at each 
step. A logarithmic scale was 
thus developed by musicians 
centuries before mathematicians 
had opened their eyes, so to 
speak— 17 /is has been used for the 
approximation of this factor, 
which results in an error of less 
than one percent. It has been 
used for the construction of 



guitars and similar stringed in- 
struments for over three hun- 
dred years. 

The Delyiannis-Friend band- 
pass filter (the type used in this 
project) was first described by T. 
Delyiannis in 1968. It has a 
number of advantages over some 
other filters, such as reduced 
sensitivity to component toler- 
ances, minimal parts count, and 
a relatively easy-to-understand 
design algorithm. It has been de- 
scribed as a bridged-T RC circuit 
with an op-amp to provide nega- 
tive feedback. 

There are only two parameters 
needed to design a bandpass fil- 
ter. They are the center frequency 
desired for the passband. and the 
Q, or quality factor. The band- 
pass filter in its simplest config- 
uration is shown in Fig. 3. That 
filter has a bandpass center fre- 
quency of 1/2ji Hz. The first step 
in designing is to assign numer- 
ical values — that is, substitute 
the Q required. Assuming a Q of 
4, 1/2Q = 0.125. and 4Q S = 64. 

After assigning numerical val- 
ues for each of the components, 
the filter is scaled up in frequency 
by dividing the capacitor values 



42 






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IMttOfftSS flow 




FIG. 2— CHRISTMAS TREE SCHEMATIC, Power for the unit is supplied by the 4 AA 
batteries or via the power jack on the back of the unit. 



by the difference in frequency re- 
quired. Assume the frequency re- 
quired is 440 Hz. The difference 
in frequency required is equal to: 

/HEwtfoLD = 440/ ( 1/2jt ' = 880jl 



The capacitor value (0.125 F] is 
then divided by this number, giv- 
ing 4.52 x 10 ~ 5 , the new capaci- 
tor value for our filter. 
The next step, scaling to real- 



istic values, is best described by 

an analogy. In an RC network, the £ 

time constant remains un- 2 

changed if the capacitor value is cd 

divided by any constant, just as 3 

long as the resistor values are £ 

multiplied by the same constant, o 



43 





PARTS LIST 




All resistors are Vi-watt, 5%, un- 


Bargraph1-Bargraph4 — 50 LED's, 




less otherwise indicated. 


assorted colors (3 groups of 10, 1 




R1— 10 ohms 


group of 20 — see text) 




R2, R7— 470 ohms 


Other components 




R3, R4,R6, R12, R53-R60. R66— 


MIC1 — 1-volt PC-mount electret mi- 




100,000 ohms 


crophone 




R5, R74— 2200 ohms 


J1 — coaxial barrel-type power jack 




R8, R17-R20— 100,000 ohms, 


(Shogyo SJ-0202) 




multiturn potentiometer 


S1— C&K 7000-series right-angle 




R9, R10, R29-R44 — option depen- 


SPOT switch 




dent, see text and Table 1 


B1-B4 — AA battery 




R11, R14, R15, R21-R28, R76— 


Miscellaneous: PC board, two bat- 




10,000 ohms 


tery holders (Keystone 2223), met- 




R13, R45-R52— 1000 ohms 


al frame and cover glass, six %- 




R16, R65— 1 megohm 


inch spacers, solder, a bit of Christ- 




R61-R63^7,000 ohms 


mas spirit, etc. 




R64— 75,000 ohms 


Note: The following is available 




R67— 15,000 ohms 


from ART WORKS, Box 753, St. 




R68-R73— 2400 ohms 


Francis, Kansas 67756: PC 




R75— 5100 ohms 


board, $35 each (three or more, 




Capacitors 


$30 each); Partial kit, including 




C1-C3, C6-C13— 0.022 |xF, 


PC board, all components in- 




5% metal film 


cluding S1, J1, battery holders, 




C4, C21-C29— 2.2 u.F, 


and all 1% resistors listed (does 




tantalum 


not include LED's, frame, or 




C5, C14-C18— 10 (iF, 


spacers), $90 each (three or 




tantalum 


more, $80 each); Complete kit, 




C19, C20— 1000 p.F, electrolytic 
Semiconductors 

IC1-IC6— LM324 quad op-amp 


including all of the above, plus 




50 LED's in four colors, spacers, 




flat-black metal frame, front 




IC7, JC8— CD4066 quad bilateral 


glass and mat, $125 each (three 




switch 


or more, $100 each). All prices 




IC9-IC13— LM3914 bar/dot LED 
driver 


include shipping and handling. 




Check or money order only. 




IC14— LM336Z-2.5-voft reference 


Please order early — we will do 




Q1— 2N4393 or 2N3972 MOSFET 


our best, but cannot guarantee 




Q2— 2N3906 PNP transistor 


delivery in less than 30 days. 




D1-D6— 1N4002 rectifier diode 


When making technical inquir- 




D7-D14 — 1N34 germanium diode 


ies please include a SASE. 



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The same concept happens to be 
true in an op-amp filter. That is, 
the center frequency (and Q) will 
be unchanged when this step is 
taken. 

A capacitor value of 0.022 u,F 
results in realistic component 
values across the entire audio 
band, provided the Q is not too 
high. So, since the capacitor val- 
ues will all be 0.022 \xF, we can 
divide 4.52 x 10 ~ 5 by 0.022x10 
~ e . resulting in 2,055. Both of 
the resistor values in Fig. 3 are 
then multiplied by that constant, 
resulting in 2,055 and 131,533 
kilohms. 

At this point, it is a good idea to 
check your work. The values just 
obtained should be substituted 
into the following equation: 

J = 1/2jiCvHTR2 

= l/2jr(0.022xl0 _6 x 

Vli.UbbKxl31.b33K) 

The result should be the origi- 
nal frequency. That equation can 



also be used to check the vari- 
ance in center frequency when 
standard component values are 
substituted, or to analyze an al- 
ready existing filter. 

In designing a unity-gain filter. 
a voltage divider must be added 
to the input, as shown in Fig. 4. 
Since the new Rl is one half of 
R2, that value is easy to calculate. 
For the new R3. the factor 

2Q 2 /2Q 2 -1= 2(16V2(16)- 1 
= 1.032 

is then multiplied by the old Rl, 
resulting in 2121.5. 

To raise, or enhance the Q, 
positive feedback is added to the 
filter input, as in Fig. 5. The val- 
ues for Rl . R2, and R3 of Fig. 5 do 
not need to have the same scale 
factor as used before. A fine value 
for Rl and R2 is 10K: R3 will then 
be 

10K(Q NEW /Q NEW -Q) 
or, for our example. 





_, 




' 


"Vso 




Rl K 1 
PUT 1 VM 
O— Wr^-jf-n 


:R2 


=4Q ! 

IS 


OUTPUT 




\? 











FIG. 3— A BANDPASS FILTER in its sim- 
plest configuration. It has a bandpass 
center frequency of 1/Sbi Hz. 



C1 
V» 

R1 
INPUT 2Q2 

c— w^H 



R3= 



_2QZ_ 
20M 




FIG. 4— WHEN DESIGNING a unity-gain 
filter, a voltage divider must be added to 
the input. 




FIG. 5— TO RAISE THE Q, positive feed- 
back is added to the filter input. 

10K(Q NEW /Q NEW -4) 

where Q NEW is the desired Q of 
the complete filter. The last step is 
to determine the closest stan- 
dard value for each resistor. 

There are four versions of the 
unit that can be built without 
having to make any calculations. 
The four versions are the broad- 
band option, the lower-four- 
guitar-strings option, the upper- 
four-guitar-strings option, and 
the tuning fork option. The tun- 
ing fork option is a good general- 
purpose version that will provide 
a nice display with most audio 
inputs. 

To use any of those options, 
you must refer to Table 1 : it shows 
the resistor values you'll need to 
use for the four filters to achieve 
the specified frequencies. Also, 
depending on which option you 
choose, the initial bandpass filter 
must be set up accordingly. 

lb use Table 1, first refer to the 
top section to determine the re- 



sistor values for the initial band- 
pass filter, the other four band- 
pass frequencies, and any special 
provisions for the particular op- 
tion. Then, from the bottom sec- 
tion, determine the resistor 
values for the other four filters 
according to the frequencies 
listed in the top section. The re- 
sistor numbers shown (R29, 
R33, and R37) are for filter A. For 
filter B, add 1 to the resistor 
number (for example, R29 be- 
comes R30, etc.). For filter C, add 
2 to the resistor number, and for 
filter D. add 3. 

Although you can assign any of 
the four frequencies to any of the 
four filters, the display will be 
most interesting if you use the 
lowest frequency for filter A, next 
highest for B, and so on. Note 
that where it says to delete a com- 
ponent, you should leave it out 
but DO NOT jumper the pads on 
the board. Where it says to 
jumper a component, you should 
leave it out and solder a jumper 
between the pads. 

Construction 

If you like, you can etch your 
own PC board since the foil pat- 
terns for the double-sided board 
are provided. However, an 
etched, drilled, plated-through, 
and silkscreened board is avail- 
able from the source mentioned 
in the parts list. Keep in mind 
that the cosmetic effect of the 
green mask, silver branches, and 
white snow will be lost if you 
make your own board. Locating 
the components for installation 
is also easier using the pre-made 
silkscreened board. Complete 
and partial kits for the Christ- 
mas tree are also available. 

Before beginning construc- 
tion, you have to decide on how 
you want your LED's arranged. 
The authors intention was to 
make each detected harmonic a 
separate color. However, you are 
free to arrange the LED's in any 
pattern you choose, and you can 
also use whatever colors you like. 
In any case, the silk screening on 
the pre-made board indicates 
which bar graph each light be- 
longs to; there are short white 
lines between the LED leads. The 
lines going up (from left to right) 
are for bargraph A, the horizon- 
tal lines are for bargraph B. and 
the ones going down (from left to 
right) are for bargraph C. Bar- 



TABLE 1 

Lower Four Guitar Strings Option: (E3, A3, D4, G4) 

Initial Filter Q = 1 .5 Center Frequency = 270 Hz 

R9 = 9.1 K R10 = 82K R41-R44 = 11K 

Upper Four Guitar Strings Option: (D4, G4, B4, E5) 

Initial Filter Q = 1.5 Center Frequency = 470 Hz 

R9 = 5.1 K R10 - 47K R41-R44 = 11K 

Tuning Fork Option: (A4 flat, A4, A4 sharp, B4) 

Initial Filter Q = 5.8 Center Frequency = 470 Hz 

R9 = 1.3K R10 = 180K R41-R44 = 12K 



Broadband Option: (E2, A3, B4, F6 sharp) 

(Jumper C2, delete C3) 

R9 = 1K R10 = 100K 



Note (frequency) 


R29 


E3 


(164.81 Hz) 


174K 


A3 


(220 Hz) 


133K 


D4 


(293 66 Hz) 


97 6K 


G4 


(392 Hz) 


73.2K 


A4 


flat (415.3 Hz) 


69. 8K 


A4 


(440 Hz) 


66.5K 


A4 


sharp (466.16 Hz) 


61 .9K 


B4 


(493.88 Hz) 


59K 


E5 


(659.26 Hz) 


44.2K 


E2 


(82 Hz) 


11K 


A3 


(220 Hz) 


4.22K 


B4 


(493.88 Hz) 


1.8K 


F6 


sharp (1480 Hz) 


620 ohms 



delete F 


R41-R44 


R33 


R37 


5.62K 


348K 


4.22K 


261 K 


3 16K 


196K 


2.37K 


147K 


2.26K 


140K 


2.10K 


130K 


2K 


124K 


1.91K 


118K 


1.40K 


88.7K 


delete 


680K 


delete 


261 K 


delete 


118K 


delete 


39K 



NOTE: All versions except the broadband option require 1% resistors. 



y> ■ • • „ift 9 9 _* r* O O 9 




(JM I €% \*f*\* < M H M i 1 1 1 1 1*!! 1 1 1 I M I * M 1 1 1 * M I M 1 1 1 1 I M M jT\^t I * I J * t 



\* 8 INCHES 

COMPONENT SIDE of the Christmas tree at half the actual size. 



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FIG. 6 — ALL OFTHE COMPONENTS mount on thefrontofthe board, with theexception of 
J1 and SI; they mount on the solder side. Use a separate color for each LED bargraph. 



graph D is indicated by the ab- 
sence or a short white line. 

When installing the compo- 
nents, start with the LED's, as 
shown in the parts-placement di- 
agram of Fig. 6. The letters next 
to the LED's indicate which bar- 
graph they belong to. You should 
probably spend a minute or so 
looking at how the LED's are ar- 
ranged on the printed circuit 
board because, once the device is 
assembled, the pattern becomes 
very confusing and the short 
white lines are covered by the 
LED's. 



The LED's are installed with 
the cathode (the flat side) toward 
the bottom of the board. Its best 
to first solder one lead of each 
LED and then check for uniform 
positioning. Straighten them out 
where necessary, and then solder 
the other leads. Remember, that 
if you want to interface your tree 
to other circuitry later on, to leave 
enough extra lead on the back of 
the board to allow a wire-wrap 
connection to be made. Be sure 
to work carefully, so that you'll be 
able to bring out this project for 
many a Christmas to come. If you 



install all the components prop- 
erly, it's very likely that the device 
will operate correctly right off the 
bat. 

From the photo in Fig. 7, you 
can see the six spacers that are 
installed on the board to hold it 
in place within the metal frame. 
It's a good idea to install the 
spacers now, since they will pro- 
tect the LED's from being 
damaged and can also support 
the board steadily. Now continue 
installing the rest of the compo- 
nents on the board. 

You must now decide what fre- 



46 



^ ci53yi S^^ i ; ]IS 




SOLDER SIDE of the Christmas tree at half the actual size. 




FIG. 7— THE SPACERS THAT HOLD THE BOARD in place in the metal frame Should be 
installed early to prevent damage to soldered components. 



quencies your Christmas tree 
will respond to. If your device is to 
be an assistance to the hearing- 
impaired, the broadband option 
will be the best, as both low fre- 
quencies and the high pitch of a 
police siren will be detected. For a 
musical version, you will have to 
make a decision based on your 
instrument of choice. Perhaps 
you can consult with a musician 
friend on this. You can re-tune 
the device at any time by simply 
changing a few resistors. All the 
components required for each 
suggested version are included in 
the kit. Remember that the ini- 
tial filter must be "in harmony" 
with the other filters. They can- 
not detect frequencies that the 
initial filter doesn't pass. Refer to 
Table 1 when choosing frequency 
determining resistor values, or 
you are free to calculate your own 
values. 

A word to the wise: put a set of 
batteries in the holders before 
soldering them. If you don't, the 
contacts on the battery holders 
are too close together which 
makes battery changing ex- 
tremely difficult. Also, remember 
that the ON/OFF switch and the 
DC power jack mount on the sol- 
der side of the board as indicated 
by the dashed lines in Fig. 6. 

Checkout 

After checking for incorrectly 
installed components, poor sol- 
der joints, and shorts, and mak- 
ing sure to correct any problems, 
install a set of batteries or con- 
nect a 6-volt power source to the 
power jack. Turning the power 
switch on will cause many of the 
LED's to light. After which point, 
they will step down to position 
one, then go out. This is normal 
operation as the device ap- 
proaches steady state. Slowly in- 
crease the gain of the initial am- 
plifier by turning R8 clockwise. 
Go back and forth between one of 
the level-adjust potentiometers 
and R8, increasing them a little 
bit each time until one of the bar- 
graphs responds to the sound of 
your voice. Make sure that none 
of the potentiometers are set too 
high, as troublesome oscillations 
may occur. 

Alternatively, connect a volt- 
meter to the junction of R15 and 
R16 and increase the setting of 
R8 until speaking directly into 
continued on page 90 



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47 






BUILD THIS 
TELEPHONE 
CALL SCREENER 




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48 



LAST MONTH WE COVERED ALL OF 

the operating theory concerning 
the CallScreen unit. This month 
we will finish up the story by 
building the unit. 

Construction 

Construction of the CallScreen 
essentially involves stuffing the 
two PC boards: the main board 
and the front- panel board. The 
use of PC boards with plated- 
through holes will greatly ease 
and speed up the assembly. 

The main PC board includes 
circuitry for the call routing 
adapter (CRA). The parts- place- 
ment diagram for the main board 
is shown in Fig. 3. If that feature 
is not going to be used, the CRA 
corner of the PC board can be re- 
moved with a hack saw. Then the 
ringer transformer can be placed 
in the cutout space. That will re- 
sult in a very compact unit if a 
wall-type power transformer is 
used. Also, the CRA can be con- 
nected as an outboard unit in its 
own project box; all you have to 
do is make the nine connections 
to the main board. You can com- 
bine CRA switches S101 and 
S102 into a single DPDT center- 
off toggle switch. 

The telephone input/output 
connections to the main board 
are made using a standard tele- 
phone extension cord cut in half, 
with the cut ends soldered di- 
rectly to the main board. That 




Get ready to give 
out your access 
codes, but only to 
the people 
who you want 
to hear from! 



JOHN G. KOLLER 



makes it easy to place the Call- 
Screen out of sight. The CRA 
jacks, however, are mounted di- 
rectly to the PC board. Al! parts 
on the main board are mounted 
on the component side. 

The parts- placement diagram 
for the front-panel PC board is 
shown in Fig. 4, All parts mount 
on the component side of the 
board with the exception of the 
six DIP switches and the two 
screen-status Indicators (LED1 
and LED2); those parts mount 
on the solder side so they can pro- 
trude through the front-panel 
cutouts (see Fig. 5). 

The builder may wish to sim- 
plify both the assembly and cut- 
ting out the front panel by 




eliminating the six DIP switches. 
You can simply hard wire your 
selected codes during assembly. 
Future code changes could be 
made but would require moving 
jumper wires. Hard wiring of ac- 
cess codes is done by soldering a 
2-inch wire to the common foil of 
each of the six DIP-switch traces. 
The wires are then soldered to the 
selected digit pads. Figure 4 
shows the outline of the code-se- 
lector switches and the digits 
(1—9) accessed by each switch po- 
sition. Remember that as the DIP 
switches are on the solder side. 
When soldering components to 
PC boards without plated- 
through holes, always make sure 
that the leads are soldered on 
both sides. Missed solder con- 
nections are a frequent source or 
problems during the initial 
check out. Also, if a PC board 
without plated-through holes is 
used, hard wiring of the code 
connections is recommended. 
That's because, with the DIP 
switches in place, top soldering 
cannot be done. However, one 
way around that is to use adhe- 
sive copper foil attached to the 
bottom of the switch body and 
soldered to the common row of 
connections. The end of the cop- 
per foil is then brought out from 
under the end of the switch and 
connected to the common foil. A 
copper pad without holes is pro- 
vided on the foil for this purpose. 



TO FRONT PANEL 




FIG. 3— PARTS-PLACEMENT DIAGRAM for the main board. Note that the CRA parts also 
mount on this board, although the two circuits are completely separate. 



On the assembly drawing for 
the front-panel PC board (Fig. 4), 
leads are shown for the loca! 
screen-mode select switches. 
When used . they are simply SPST 
momentary pushbtittons. Typ- 



ically, they are not used since 
most modern telephones are of 
the Touch-Tone" type, and 
screen-mode changes can be 
made from any such phone con- 
nected to the CallScreen output 



jack. When the CRA is switched 
on, remote screen selection from 
connected telephones is auto- 
matically disabled as a security 
measure in case an answering 
machine or FAX machine an- 



CODE SELECTION 



DIGIT 

SEQUENCE 




PRIMARY 
CODE 



♦MOUNTS ON SOLDER SIDE 



FROM MAIN BOARD 



FIG. 4— PARTS-PLACEMENT DIAGRAM for the front-panel PC board. The DIP switches 
can be left out if you hard wire the access codes. 



D 

in 
o 

m 

00 

m 

33 

_k 

to 
(O 
o 



53 



CALLSCREEN PARTS 



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All resistors are Vi-watt, 5%, un- 
less otherwise noted. 

R1, R10, R46, R57, R65, R68— 1 
megohm 

R2. R5, R7, R17-R19, R23, R26, 
R32, R33, R36-R42, R52-R55, 
R58. R60, R63. R67, R70, R75— 
10,000 Ohms 

R3, R27— 560 ohms 

R4, R29, R71— 47,000 ohms 

R6— 560 ohms, Vi-watt 

R8 — metal-oxide varistor (MOV) sur- 
ge suppressor, 130 VRMS, 15 
joules 

R9-not used 

R11, R 12— -2200 ohms 

R13-R16, R20, R24, R25, R30, R31, 
R34, R45. R61— 100,000 ohms 

R21— 680,000 ohms 

R22. R50— 4700 ohms 

R28— 680 ohms 

R35— 51 ,000 ohms 

R43, R44— 180 ohms 

R47-R49— 200,000 ofims 

R51— 2000 ohms, potentiometer 

R56— 390,000 ohms 

R59— 100 ohms 

R62, R 74—470 ohms 

R64— 150 ohms, !<->-watt 

R66— 82.000 ohms, 1% 

R69— 33,000 ohms 

R72— 220 ohms 

R73— 10 ohms 

Capacitors 

C2, C3, C16, C17, C19. C20, C23, 
C25, C28-C31, C39, C47, C56— 
0.02 (j,R 20 volts, ceramic disc 

C4, C10, C21, C52— 22 fiF, 16 volts, 
radial electrolytic 

C5, C15, C22. C24, C26, C33, C49, 
C50, C51, C54, C55, C57— 0.1 |aF, 
20 volts, ceramic disc 

C6-C9— not used 

C11— 0.33 p.F, 250 volts, poly- 
propylene 

C12— 0.47 \lF, 250 volts, poly- 
propylene 

C13— 10 m-F. 50 volts, axial elec- 
trolytic 

C14— 2200 fxF, 25 volts, radial elec- 
trolytic 

C18— 100 ^lF, 10 volts, radial elec- 
trolytic 

C27— 4,7 u,F, 10 volts, axial elec- 
trolytic, non-polarized 

C1 , C32, C34, C35. C40, C48, C58— 
10 (xF, 10 volts, radial electrolytic 

C36— 0.039 m-F, 20 volts, ceramic 
disc 

C37— 0.01 |xR 20 volts, ceramic disc 

C38, C53— 0.05 |xF, 20 volts, ce- 
ramic disc 

C41, C45—470 ^F. 10 volts, radial 
electrolytic 

C42, C46— 0.22 |aF, 50 volts, poly- 
ester 

C43— 1 jxF, 35 volts, tantalum 

C44 — 4700 iaF, 16 volts, radial elec- 
trolytic 



swers a processed call. It is done 
so that the screen modes cannot 
be changed be the caller during 






Semiconductors 

IC1— LM1458 dual op-amp 

IC2. IC25— LM741 op-amp 

IC3— MC4001 quad NOR gate 

IC4, IC12-IC14, IC22— MC4081 
quad AND gate 

IC5— SSi 202 DTMF receiver (Sil- 
icon Systems, Inc.) 

IC6— MC4028 BCD-to-decimal con- 
verter 

IC7— TCM1520 ring detector (Texas 
Instruments) 

IC8, IC21— 4N33 Darlington opto- 
coupler 

IC9— MC4071 quad OR gate 

IC10, IC28— MCT-2 transistor opto- 
coupler 

IC11. IC20, IC24, IC27— MC4011 
quad NAND gate 

IC18— MC4013 dual D-type flip-flop 

IC15-IC17, IC23— MC4017 decade 
counter 

IC19— MC7805 5-voit regulator 

IC26— LM383 7- watt power amplifier 

D1, D2, D35, D40— 5.1-volt Zener di- 
ode 

D3-D10, D12-D18, D20-D32 
D36-D39, D41—1N914 diode 

D11, D19 D33. D34— not used 

Q1-Q4— 2N4401 NPN transistor 

BR1— 50-PIV1.5-amp bridge rectifier 

BR2, BR3— 100-PIV 0.5-amp bridge 
rectifier 

Other components 

T1— 120712VAC 950 milliamp power 
transformer 

T2— 600'600-ohm telephone line 
coupling transformer 

T3— 8.8K ohm 10 -watt matching 
transformer (use 8-ohm and 0.625- 
watt taps on a 70-volt line trans- 
former) 

XTAL1— 3.58-MHz colorburst crystal 

S1, S2— SPST momentary pushbut- 
ton switch 

S3-S8— 9-position DIP switch 

RY1— SPST N.O. miniature relay, 5- 
volt, 70-ohm coil {or nearly any 
other 5-volt miniature relay) 

RY2— DPDT miniature relay, 12-volt, 
290-ohm coil (between 260-400 
ohms) 

CALL ROUTING ADAPTER PARTS 
All resistors are Vi-watt, 5%, un- 
less otherwise noted. 

R101— 150 ohms, Vi-watt 

R102, R1 03— 10,000 ohms 

R104 — 330 ohms 

R1 05— 1000 ohms 

Semiconductors 

D101-D106— 1N914 diode 

Q101, Q102— 2N4401 NPN transistor 

Other components 

RY101, RY102— SPDT miniature re- 
lay, 12-volt, 320-ohm (nominal) coil 

S101, S1 02— SPDT miniature switch 
(or use single DPDT center-off 
switch) 



the seven-second "window" when 
an off-hook is raised at the Call- 
Screen/CRA output. If call rout- 



C0PYRIGHT /1TN 
I 1968 J.G.Koller HH 



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7"fc 






re - 



"75" 



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•ST! 
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1188- P • 



COMPONENT SIDE of the front-panel PC 
board, at full size. 



ing is desired for telephones only, 
then the remote screen selection 
feature should remain available 
all the time. That is achieved by 
leaving out the jumper wire from 
the CRA terminal E to the main- 
board TPV. 
When the two boards are 



54 




COMPONENT SIDE of the main circuit board, shown here at half of its actual size. 



■ ■•hi •iiiiiiij 






m m 



<1 



tVJtK f 2Hr 



. . [VJj_jj.d.. LL^ 



-8 INCHES - 



SOLDER SIDE of the main circuit board, shown here at half of its actual size. 




FIG. 5— THE SIX DIP SWITCHES and the two screen-status indicators (LED1 and LED2) 

must be mounted on the solder side of the front-panel board so that they can protrude 
through the cutouts on the cabinet. 



ORDERING INFORMATION 

Note: This information supersedes 
that presented last month. The follow- 
ing is available from Electronic Control 
Systems, R.D. 2 Box 3308, wer- 
nersville, PA 19565: A set of two dou- 
ble-sided, plated-through PC boards 
for S39.95 (add $2.00 postage and han- 
dling); a complete kit including PC 
boards and all parts except the cabinet 
for $139.00 (add $3.50 postage and 
handling). Pennsylvania residents add 
6% sales tax to all orders; check or 
money order only. 



finished they are connected to- 
gether and mounted at a right 
angle to each other in the cab- 
inet. But remember to inspect all 
wiring and solder joints for poor 
or non-existent connections be- 
fore doing so. All interconnec- 
tions between the two boards 
should be made with fine gauge 
hook-up wire (AWG 30) to reduce 
mechanical stress on the boards 
during assembly. The boards 
may be installed in any type of 
cabinet the builder wishes. If the 
LED indicators are panel 
mounted and the code-select DIP 
switches are replaced with hard 
wire jumpers, then the front- 
panel board can be mounted any- 
where inside the cabinet. 

The two power ICs (IC19 and 
IC26) must be heat sinked. Their 
location on the PC board allows 
them to be bolted directly to the 
cabinet wall using 6-32 hard- 
ware. (Make sure that the nuts 
used are not so large that the IC 
cases crack when tightened 
against the tabs). Both IC heat- 
sink tabs are at ground potential 
so they do not require insulating. 
If a plastic cabinet is used, a strip 
of aluminum sheet metal may be 
mounted to the tabs as a heat 
sink. The majority of heat gener- 
ated occurs when the screener is 
ringing telephones, so large 
sinks are not needed. A l-x5- 
inch strip of aluminum should 
be sufficient. 

Power-up 

Set the ring-voltage potentiom- 
eter (R51) to an initial 10-O'Clock 
position. If possible, adjust the 
ring voltage to 90 volts using a 
DMM and an REN load of 1.0. If 
the CRA is used, make sure it is 
switched off. Connect the Call- 
Screen to a phone line. Lift the 
receiver and check for a dial tone. 

Connect an ohmmeter across 



55 



Put Professional Knowledge and a 

COLLEGE DEGREE 

in your Technical Career through 

HOME ™ 
STUDY -^ 




a 



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EC 



Add prestige and earning power to 
your technical career by earning 
your Associate or Bachelor degree 
through directed home study. 

Grantham College of Engineering 
awards accredited degrees in 

electronics and computers. 

An important part of being pre- 
pared to move up is holding the 
right college degree, and the abso- 
lutely necessary part is knowing 
your field. Grantham can help you 
both ways — to learn more and to 
earn your degree in the process. 

Grantham offers two degree pro- 
grams — one with major emphasis 
in electronics, the other with major 
emphasis in computers. Associate 
and bachelor degrees are awarded 
in each program, and both pro- 
grams are available completely 
by correspondence. 

No commuting to class. Study at 
your own pace, while continuing 
on your present job. Learn from 
easy-to-understand lessons, with 
help from your Grantham instruc- 
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Write for our free catalog {see address 

below), or phone us at toll-free 

1-800-955-2527 (for catalog requests 

only) and ask for our "degree catalog." 

* 

Accredited by 

the Accrediting Commission of the 

National Home Study Council 

GRANTHAM 

College of Engineering 

250 Frontage Road 

Slidell, LA 70460 



the + 5-volt supply line and make 
sure that no low resistances exist 
(less than IK). Similarly, check 
the + 16-volt supply line for any 
resistance under 15K. Connect a 
DC voltmeter across the 5-volt 
supply, power up the unit, and 
check for the proper voltage. AJso 
check the 16-volt supply; under 
idle conditions it should read 
close to 18 volts. 

Lift the receiver of the tele- 
phone and check for screen mode 
changes using the "#" and '**" 
keys. Leave the screen mode in 
"Limited Screen" (one LED lit). 
Note that screen mode changes 
via a connected phone are al- 
lowed for only seven seconds fol- 
lowing an off-hook transition. 
Using two telephones connected 
to the CRA output jacks, have a 
caller enter each code, and also 
no code, with the CRA in each of 
its two modes. Verify that call 
routing occurs. 

In a similar manner, cause one 
phone to ring but answer the call 
through the non-ringing phone. 
Verify that the incoming call is 
properly answered. Repeat the 
step using the other telephone. 
Verify that outgoing calls can be 



Try the 

ClEEtrDtliES 

bulletin board 
system 

(RE-BBS) 
516-293-2283 

The more you use it the more 
useful it becomes. 

We support 300 and 1200 baud 
operation. 

Parameters: 8N1 (8 data bits, no 
parity, 1 stop bit) or 7E1 (7 data 
bits, even parity, 1 stop bit). 

Add yourself to our user files to 
increase your access. 

Communicate with other R-E 
readers. 

Leave your comments on R-E with 
the SYSDP. 

RE-BBS 
516-293-2283 




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•ooo~£J 



77. 



90 4/ 



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SOLDER SIDE oi the front-panel PC 
board, at full size. 



made by either phone regardless 
of the CRA mode. Be sure to re- 
view last month's article for a dis- 
cussion of all screening features. 
The detailed circuit description 
should help you to troubleshoot 
any problems. Then you're ready 
to give out your access codes! R-E 



56 




SUSIE simplifies digital design, and makes 
breadboards a thing of the past 



TJ BYERS 



DESIGNING DIGITAL CIRCUITS MAY 

look like child's play, but the jour- 
ney from inspiration to a func- 
tional circuit is fraught with 
peril. Propagation delays, glit- 
ches, timing violations, and bus 
conflicts can turn a simple idea 
into a nightmare. 

The traditional method of test- 
ing a digital design is to bread- 
board the circuit, then drag out 
the logic probe, oscilloscope, and 
logic analyzer to find out why it 
doesn't work. The modern meth- 
od is to simulate the design on an 
IBM-compatible PC using a pro- 
gram called SUSIE (standard 
universal simulator for improved 
engineering), made by a compa- 
ny called Aldec. 



If you knew SUSIE 

SUSIE is a simulation program 
that graphically depicts the tim- 
ing and logic events of a digital 
circuit. Although SUSIE uses 
software to verify the design, the 
results are the same as if you had 
built the circuit and used an ul- 
tra-sophisticated logic analyzer 
to test and debug it. 

SUSIE simulates the operation 
of logic IC's using mathematical 
models stored in a library. IC 
models include algorithms for 
setup and hold time, pulse wid- 
th, edge-to-edge transfer delay, 
and other propagation param- 
eters. 

There are different libraries for 
different types of components, 
with one library for TTL devices, 
another for CMOS, yet another 



for ECL, and so on. SUSIE comes 
with those three libraries, plus 
two additional libraries con- 
taining switches and other pas- 
sive components. Aldec's Model 
Builder Compiler (MOBIC) allows 
you to model IC's that are not in- 
cluded in the libraries. You can 
also purchase extra libraries for 
devices including memory IC's, 
microprocessors, gallium-arse- 
nide {GaAs) logic, programmable 
logic devices (PLD's), and gate ar- 
rays, plus libraries for computer 
interfaces and industrial compo- 
nents like stepper- motor control- 
lers. The optional libraries cost 
between 6800 and $2,000. How- 
ever, you can do a lot with the 
nearly 6000 devices that come 
standard with the basic SUSIE 
package. 



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57 



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PRODUCTS MENTIONED 

SUSIE 

Aldec Co. 

3525 Old Conejo Rd. #111 

Newbury Park. CA 91320 

(805) 499-6867 

OrCAD 

OrCAD Systems Corp. 

1049 S.W. Baseline St. 

Suite 500 

Htllsboro, OR 97123 

(503) 640-9488 

SuperCAD 

Mental Automation 

5415 136th Place S.E. 

Bellevue, WA 

(206) 641-2141 



A SUSIE example 

To understand how SUSIE 
works, let's take an example. The 
circuit shown in Fig. 1 is a divide- 
by- five counter with a 50% duty 
cycle. Ordinary divide-by-5 coun- 
ters produce an asymmetric out- 
put with a 20/80 timing ratio, 
but by using a negative edge-trig- 
gered flip-flop and half-state tim- 
ing, we can make a divide-by- five 
counter with a 50/50 timing 
ratio. 

Three counter stages are 
needed to divide by five, with one 
driven on the inverted clock to 
compensate for the odd number 
of states. That is, to achieve the 
sixth state needed to produce a 
50% duty cycle, ICl-b must 
change state on the negative edge 
of the clock at r=2.5. and that 
can be forced by timely triggering 
of the flip-flop's preset input (pin 
10). 

Debugging a circuit like that in 
hardware could get quite thorny. 
Let's see how SUSIE handles the 
situation. 

Design entry 

SUSIE's design verification 
process is divided into three 
steps: design entry, test vectors, 
and simulation. During design 
entry you load and define the sec- 
tion or sections of the circuit you 
want to display on the screen. 
SUSIE can show as much or as 
little of the design as you wish. 
You can zoom in on a single IC or 
display waveforms for every point 
in the circuit. 

Design entry begins with a 
netlist. The netlist contains a list 
of all the components in the cir- 
cuit and their connections to one 



IN1 

o— 



J PR Q 

IC1-a 
Va74LS11Z 

CLK Ht 

K CLR 



T 




6 8, ^^ 

IC3-c\ 10 
• 74LSD2 



A 



K CLR q 

IC1-b 
1 ft74L511Z 

OK, ^D 



T 



9 1 



to 



1 



J PR D 

!C2-a 

'ft74LS112 

«3 OR° 



15 



V* 0UT1 



1C3-BN. 4 
I74 74LS02) 




FIG. 1— DIVIDE-BY-FIVE counter with a 50% duty cycle output. 



i Ul-2.... 
UI-5 

i UMZ... 
i Ui-13... 
i Ul-IQ... 



— Stin.l — 4-Break. 



" i 



520 ns 



Top line: 



U2-7 . . 
i U2-13. 

1 UZ-11. 
i U2-12. 



9^0000111111+80= 15ns "-> 

■■ S initiate 

|Similate: que step=[Ll,t+h{Enter> fast=IR],{-J a«to=tL*BhtIns>; {F2>=nore-> 

-■ fia2.net 



g node: I j Scale: ions i i- i > i It m >■* i Prop; au.q 
FIG. 2— SUSIE SIMULATION of the divide-by-5 counter siiown in Fig. 1 



another. SUSIE reads the netlist, 
downloads the specified compo- 
nents from their libraries, and 
"builds" the circuit in RAM. (See 
the sidebar, "Writing A SUSIE 
Netlist," for more information 
about netlists.) 

After SUSIE loads the netlist, 
you define which part(s) of the 
design you want to view by listing 
pin numbers or node names in 
the signal column on the left side 
of the display screen. For exam- 
ple, in Fig. 2, we defined several 
nodes (INI, OUT1) and various 



pins oflCl and IC2 for display 

Note that we selected no pins 
from IC3, and only some from IC1 
and IC2. The reason is that too 
much information can be more 
confusing than not enough. The 
point is that, regardless which 
nodes are displayed, the entire 
circuit is tested during simula- 
tion, and all questionable timing 
events (glitches, etc.) are brought 
to your attention. 

Of course, after creating a de- 
sign, you can save it to disk and 
load it again later. 



58 



= Stin.l=;Bre«k 



HI 





; i Jl-Z., 
a Ul-5.. 
i U1-1Z. 
i Ul-13. 

i Ul-10. 

i UZ-3., 

o 112-5.. 

b IIZ-6.. 

o U2-7. . 

i UZ-13. 

Si UZ-11. 

i UZ-L2. 



p+eooieoiiietB- 

p Sinulate ; 

Sinulate: one step^LLW, {Enter) fast=[R],{) auto=[l*Rl,{Ins); {F2}=more-> 

' fig3.net 



m nuae: F 



Scale: 



10ns 



i- 



-f m 1 1 



li R Prop^_agg 



FIG. 3— DIVIDE-BY-THREE counter created by changing the test vector on pin 10 of IC1 to 
pull pin 12 high. The original circuit (Fig. 1) becomes a divide-by-3 counter with a 50% duty 
cycle. 



Signal -» Stin,4=lBreak 



i Ut-2., 

o Ui-5. . 

i Ui-iZ. 

i Ul-13. 



i Ul-10. 

o UZ-7.. 
i UZ-13. 
i UZ-11. 
i UZ-12. 

<i U3-5.. 




Out ions 54-Break;->i<-Glitc)»-ri 



j Delete 



3-*0001000010*-BO= 15ns "-4 
- Sinulate 

Sinulate: one step=[Lh{+), (Enter) fast=[R],{) auto=H*Rl,{Ins}; {FZJ=more-> 

; fig4.net 



node: 1 B Scale: 



?ns 



:-> g I' . '! i Prop: Aug 



FIG. 4— SUSIE SIMULATION of the complete divide-by-3 counter. 



Test vectors 

For a design to function, it 
must have some kind of input; 
SUSIE's inputs come from test 
vectors. A test vector is nothing 
more than a waveform that, 
when applied to an input, causes 
something to happen in the cir- 
cuit. SUSIE can serve up an al- 
most limitless variety of test 
vectors. 

You create test vectors using ei- 



ther an ASCII text editor or SUS- 
IE'S built-in test-vector editor. 
Test vectors may be stored in ei- 
ther a compressed binary format 
or one of three ASCII formats. 
The ASCII versions differ both in 
the format of the file and in the 
way it is used. 

• The line version is formatted as 
a string of l's (high) and O's (low) 
that establishes the timing and 
shape of the waveform. Each line 



in the file represents one wave- 
form, and you may describe and 
load as many lines (waveforms) 
as you wish. 

• The bus file is similar to a line 
file, except that it is written in 
hexadecimal notation, and is 
used primarily to define wave- 
forms for an entire bus. 

• The waveform file consists of 
statements written in Aldec's pro- 
prietary high-level language, and 
it can be used to create wave- 
forms too complex for the other 
methods. 

To use SUSIE'S built-in editor, 
you simply place the cursor over 
the signal to be edited and man- 
ually key in the desired wave- 
form. After the test vector 
appears satisfactory, you can 
save it to a line or bus file directly 
from the screen. However, test 
vectors created on the screen 
using Aldec's programming lan- 
guage cannot be saved to a file; 
you can retain such files only by 
creating them first with a text ed- 
itor. 

After defining and naming a 
test vector, you can load it into 
any netlist design entry. Al- 
though a test-vector file may con- 
tain any number of waveforms, 
only one file may be loaded at a 
time. 

SUSIE also has an internal ten- 
stage binary counter that can be 
used along with a test-vector file 

OBTAINING SUSIE 

As digital circuit-simulation pro- 
grams go, SUSIE is a real bargain. 
But at $995 {optional libraries not in- 
cluded), it's too pricey for the average 
hobbyist. 

Fortunately, Aldec offers a free 
SUSIE demo disk that does every- 
thing the full-blown SUSIE package 
does, but on a smaller scale. Instead 
of 6000 devices, the demo contains 
26 logic devices and seven PLD's, 
plus a full complement of switches 
and passive components. 

Although the demo disk can't simu- 
late every digital design situation, the 
logic types are varied enough that, 
with prudent part selection, you can 
test a wide variety of design types — 
for free. Table 1 lists the IC's sup- 
ported by the demo disk. The letters 
xx stand for any logic technology, ie. 
LS, AS, F, etc. IC models include set- 
up and hold time, pulse width, edge- 
to-edge and other propagation delay 
parameters. r-e 



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TABLE 1— DEMO DISK SUPPORTED COMPONENTS 





74xx00 


Quad 2-input NAND gate 




74xxQ2 


Quad 2-input NOR gate 




74xx04 


Hex inverter 




74xx05 


Hex inverter (OC) 




74xx07 


Hex buffer (OC) 




74xx08 


Quad 2-input AND gate 




74xx10 


Triple 3-input NAND gate 




74xx1 1 


Triple 3-input AND gate 




74xx20 


Dual 4-input NAND gate 




74xx30 


8-input NAND gate 




74xx74 


Dual D-type flip-flop 




74xx85 


4-bit magnitude comparator 




74xx86 


Quad 2-input XOR gate 




74xx90 


BCD decade counter 




74XX138 


3-of-8 decoder 




74xx1 51 


8-input multiplexer 




74xx1 53 


Dual 4-input multiplexer 




74xx157 


Quad 2/1 multiplexer 




74xx161 


Presettable binary counter 




74xx175 


Quad D-type flip-flop 






74xx193 


BCD up/down binary counter 




74xx244 


Octal driver Three-state 




74xx245 


Octal bus transceiver 




74xx279 


Quad S-R latch 




74xx373 


Octal transparent latch 




74xx374 


Octal D-type flip-flop three-state 




10H8 


PLD 




16L8 


PLD 




16R4 


PLD 




20L8 


PLD 




20L10 


PLD 




22V10 


PLD 




32VX10 


PLD 



























.« 




0UT1 


8 T 








1?l 










'■ ■ 




3 


J PR 
ICt-a 
V? 74LS112 

CLK K OR Q 








'/4 74LS02)O- 


13 


COC K CLR q 

IC1-b 
V2 74LS112 

J PR Q 


1 

9 


e 








IN 1 




2 


r 










% 


10 






i 


















13 


Vcc 


















. 










11 


J 
K 


CLK PR o 

IC2-b 
'ft74LS112 

clr 


7 


5 \ 




£3 


\ IC3^a\ 1 -p 
1V.1 74LSD2>0 1 








I 


C3-tf\ 4 


6 1 






L 


































v, 


r 
c 











FIG. 5— FINAL SCHEMATIC of the divide-by-3 counter. 



w 
o 
z 
o 

EC 

L±J 



o 
5 
< 



as a square- wave signal gener- 
ator or as a frequency divider for 
other test vectors. 

Simulation 

Circuit simulation is the third 
and final step in the simulation 



process. It is where you get to see 
what happens in the circuit as a 
result of the applied inputs. Its 
also where you learn whether or 
not your design will fly. 

The simulation mode provides 
numerous features that simplify 



analysis. You can preset any de- 
sign element to an initial logic 
state, search for timing glitches, 
and set breakpoints for incre- 
mental timing measurements. 

Most simulations use the inter- 
nal binary counter for the signal 
source, as we did for our test de- 
sign in Fig. 1. The counter has 
ten stages (BO through B9), each 
of which is half the frequency of 
the preceding stage. The pulse 
width of BO is adjustable between 

10 picoseconds and 999 seconds. 
For our simulation, we set BO at 
15 ns and used Bl (30 ns) as the 
clock. The resulting display is 
shown in Fig. 2, which we will 
now use to verify our design. 

At power up (r = 0). the output 
of ICl-b (pin 9) is set high. On the 
first clock pulse, the input to pin 
13 goes negative, causing the flip- 
flop to toggle and force pin 9 low 
and pin 7 high. That sets the 
stage for ICl-a to reset on the fall- 
ing edge of the same clock pulse, 
which in turn causes pin 12 to go 
low and prevents further clock 
pulses from affecting ICl-b. 

However, IC2-a continues to to- 
ggle, sending signals to IC2-b un- 
til its inputs reach a logical 
combination (pin 11 high, pin 12 
low) that causes the inverted out- 
put (pin 7) to go low on the falling 
edge of the third clock pulse. 
That forces ICl-bs preset input 
(pin 10) low and output (pin 9) 
high. A half state later, ICl-bs 
new logic state forces IC2-b's pin 

1 1 input low. That releases the 
hold on (Cl-b and enables the 
counter to function as a normal 
state machine until the forced 
state is reached again. The re- 
sulting waveform at OUT1 shows 
us that our design does indeed 
work as predicted. 

Using SUSIE to modify a design 

Unlike many analog and digital 
simulators, SUSIE doesn't need 
to compile the netlist before it 
can do a simulation, and that 
makes it possible to change test 
vectors and circuit connections 
without having to change the 
netlist. 

For example, let's say that we 
wanted to modify our design so 
that it was a divide-by-3 counter 
instead of a divide-by-5 counter. 
That is easily done using SUSIE's 
on-screen editing features. 

Looking at the timing screen in 
Fig. 2, we see that in order to pull 



60 



LISTING 1— NETLIST OF DIVIDE-BY-3 COUNTER 


sockets u1=74LS112 




sockets u2 = 74LS11 2 




sockets u3 = 74LS02 




/in1,u1/1,u2/13, u3/8, u3/9 


;signal input 


/out}, u1/2, u1/9, u3/5 


;divide-by-3 out 


u1'3, ul/7 




u1/6, u3/6 




uL'10, u2!7 


;U1b preset 


U1/13. u3'10 




u2/1 1 , u3/2, u3/3, u3/4 




U2/12, U3/1 




/GND, u1/8, u2/8, 03/7, U 1/11 




A/CC. u1/16, u2'16, u3/14, u1/4, 


u1/15, ul/14, ut'12, u2/10. U2/14 




WRITING A SUSIE NETLIST 



Like all circuit-simulation pro- 
grams, SUSIE uses a netfist to define 
the circuit. However, unlike many cir- 
cuit simulators, which require special 
tools to create the netfist, SUSIE'S 
netlist is in pure ASCII, which means 
all you need to make a SUSIE netlist 
is a text editor. 

The process begins with a sche- 
matic of the design . ( Refer to Fig . 1 in 
the text for this discussion.) First, the 
circuit's inputs, outputs, and compo- 
nents are identified by name and 
number. Those labels are then en- 
tered into the netlist using the format: 
sockets schematic label = device 
type. The order of the parts is really 
immaterial. 

Next, connections between de- 
vices are listed by component label 
and pin number, with a comma sepa- 
rating each entry. Again no special 
order is necessary, and comments 



(placed after a semicolon) can be in- 
serted in the netlist to help describe 
large designs. Signal inputs, outputs, 
and power-supply connections are 
preceded by a slash, 

A separate line is required for each 
node in the circuit (a node is any point 
where two or more pins or wires con- 
nect). However, if the number of con- 
nections to a node is greater than will 
fit on a line, the listing can extend to 
the next line by ending the first line 
with an "&" character. There is no limit 
to the number of lines you can use for 
a single node, provided the lines are 
in sequence and linked via the "&" 
character. 

That's all there is to it. The netlist 
shown in Listing 2 is ready for simula- 
tion. Several schematic-capture pro- 
grams, including OrCAD and Super- 
CAD, can generate a SUSIE netlist 
directly from a screen schematic. R-E 



LISTING 2— NETLIST OF DIVIDE-BY-5 COUNTER 

sockets U1-74LS112 
sockets u2 = 74LA1 12 
sockets u3 = 74LS02 

/in1, u1/1, U2/13, u3/8, u3/9, u2/1 

,'out1, uV2, u1/9 

u1/3, ut/7 

u1/5, u2/3, U3/11 

u1/6, u3/6 

U1/10, u2/7 

ul/12, U3/13 

u1/13, U3/10 

u2/5, u3/12 

U2/6, U3/5 

u2/1 1 , u3/2, u3/3, u3/4 

U2/12, u3/1 

/GND, u1/8. u2/8, u3/7, ul/11 

A/CC, u1/16, U2'16, u3'14, u1/4, u1/15, u1/14, u2<4, u2/15, u2/2, u2'10, u2/14 



;signal input 
;divide-by-5 out 



;U1b preset 



this off we have to force the break 
at t= 1.5 instead of at r = 2.5. We 
can test our theory by applying a 
custom-made test vector to pin 
lOoflCl-b. 

The test vector can be created 
in several ways, but the best 
method for our situation is to use 
the Aldec programming lan- 
guage. First we look at the dis- 
play to determine where the 
changes must occur. For our ap- 
plication, the test vector must 
have eight high pulses followed 
by four low pulses. The Aldec 
equation for that waveform is 
(H8L4)100, where H8 specifies 
eight highs, L4 specifies four 
lows, and 100 indicates that the 
preceding pattern should be re- 
peated one hundred times. The 
repeat gives us plenty of time to 
play with the circuit before run- 
ning out of signal. 

To perform the modified sim- 
ulation, we load the original de- 
sign into SUSIE and apply the 
test vector to pin 10 of ICl-b (Fig. 
3 ). Analysis of the timing display 
shows that pin 12 of ICl-b needs 
to be tied high so that ICI-b isn't 
affected by IC2-a. You could go 
into the netlist and change pin 
12s connections, but SUSIE s ed- 
itor lets you assign IC pins or 
nodes to keyboard keys that 
manually override the design 
stimulus. In our case, we assign- 
ed the a key to pin 12, then tog- 
gled the input high for the 
simulation. The result of this 
simulation, shown in Fig. 3, 
shows that our assumptions 
were correct and that the new de- 
sign does work: For every three 
input pulses, the circuit pro- 
duces one output pulse, and the 
duty cycle is 50%. The netlist for 
that circuit is shown in Listing 1. 
The next step is to alter the cir- 
cuit so that it generates the test 
vector itself. This can also be 
done in SUSIE using 
connectivity markers — screen 
notations that tell SUSIE to make 
a connection between like mark- 
ers. As it turns out, the only 
change we have to make in the 
original design is move pin 5 of 
IC3 from IC2-a to pin 9 of ICl-b 
using the "aa" connectivity 
markers shown in Fig. 4. The ° 
rules for connectivity are: If you S 
mark an input for screen con- S 
nectivity, all previous connec- Eg 
tions to the input are severed; if _ 
you mark an output for screen g 



61 



Q 

Q 

< 
<x 



connectivity, it serves the new 
source plus all the original 
sources. 

Next we disconnect the Aldec 
test vector and run a new simula- 
tion, as shown in Fig, 4. Once 
again, the simulation verifies the 
circuit changes. A revised sche- 
matic of the new divide-by-three 
counter is shown in Fig. 5. 

Advanced features 

SUSIE also has a host of ad- 
vanced features that are used to 
pinpoint design defects, test for 
worst-case conditions, and input 
data from or output it to the real 
world. Here is a brief description 
of each advanced feature. 

• Switches placed in the circuit 
can be opened and closed from 
the simulation screen, making 
"what-if ' and alternate-config- 
uration designs a snap to verify. 

• The timing selection allows 
you to set IC propagation delays 
to any value for worst-case eval- 
uation. You can also change IC 
technology (for example, from LS 
to AS), save and load IC propaga- 
tion data files, and include the 
effect of temperature and loading 
on the simulation. 

• Glitches that occur as a result 
of propagation delay, timing vio- 
lations, or floating inputs are au- 
tomatically displayed and pin- 
pointed — even if the pin involved 
isn't part of the simulation dis- 
play. 

• Bus conflicts, where two or 
more outputs vie for simulta- 
neous use of the bus, automat- 
ically produce a warning mes- 
sage that can be used to pinpoint 
the conflicting signals. 

• Fault simulation, which shows 
all stuck inputs and outputs, is 
available as an option. To speed 
the lengthy process of fault sim- 
ulation, SUSIE lets you divide the 
job among an unlimited number 
of unconnected PC's. 

• Hardcopy printout of screen 
simulations can be made using 
either a dot-matrix or laser 
printer. The logic analyzer option 
lets you feed test vectors from a 
hardware design (breadboard or 
PC board) to SUSIE for analysis 
and debugging. 

While SUSIE'S simulation 
powers make it an attractive al- 
ternative to breadboarding, its 
real strength is that it lets your 
creative talent run free — without 
any physical restrictions. R-E 



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FOR A TEST TECHNICIAN OR ENC.I- 

neer. using test leads with a mul- 
tifile ttr may be an everyday 
experience. Those of you who use 
multimeters on a consisirnt 
basis know how important it Is to 
use the right kind of test lead, 
probe and probe tip. Those less 
experienced might be inclined lo 
use any old probe. We'll show you 
why that's not a good idea, and 
then we'll take a look at what's 
currently available to help you 
make the right decision in ehoos- 
igyour test probes. 






HOOSIN 
HE til 



The basics 

There are four basic require- 
ments that determine the quality 
of a good test lead. Those require- 
ments are: -^fl 

• Reliability — the lest lead 
should bite through the oxide. 
dirt, corrosion and insulation or 
conformal coating to make good 

^ contact with a lead, test point or 
wire, 
• Hold the connection — the test 
lead should keep a continuous, 
nonintermittent contact. 

• Dependability — the test con- 
nection must be insulated from 
other devices or equipment, and 
the connections shouldn't pull 
loose. That's a particularly frus- 
trating problem, especially when 
you're forced to stop testing sev- 
eral times to reconnect the leads. 
A "hot" lead swinging loose can 
also be a danger, which leads us 
to the next point. 

• Safety- — testing can be inher- 
ently dangerous in many cases, 
so it's important that the equip- 
ment be as safe as possible. 

Those four points aren't listed 
in order of priority; they are inter- 
dependent necessities. A good 
contact doesn't accomplish any- 
thing if you have 1500 volts hang- 
ing loose! With those four basic 
requirements in mind, we'll take 
a look at different probe tips, 
which actually make the test con- 
tact, as well as body design and 
interconnections. 

Types of probe tips 

One of the most commonly 
used tips is the brass-notched 
type, shown in Fig. 1-a. That type 
of tip is normally a 0.08-inch di- 
ameter brass rod, an inch or less 

•Bill Hansen is an engineering supervisor for ITT 
Pomona, a company specializing in lest lead kits 
and accessories lor digital multimeters. 




g 
z 
o 

DC 
H 
O 
LU 
— I 
LU 

g 
a 

s 



in length, with a conically- 
shaped arrow-head on the end. 
Brass is a good current conduc- 
tor with a very low voltage drop 
across the contact point. It's rela- 
tively soft so it can conform to the 
test point with some grab, and 
not slide away too easily. In addi- 
tion, the notch can lock onto a 
lead or wire, if that's what you're 
testing. The notched tip is small 
enough to fit into tight spaces 
and can handle most loads it's 
subjected to. 

A dog-leg microtip, shown in 
Fig. 1-b, is useful for probing 
high-density PC boards that use 
surface mount technology (SMT). 
It lets you dodge around compo- 
nents and provides a "spring- 
iness" that enables you to move 
the probe handle slightly without 
losing your contact point. Exten- 
dable versions allow you to reach 
several inches down into a cir- 
cuit, perhaps to get around a 
power supply or other object. 
Since these long, thin tips are 
insulated, they are not likely to 
cause shorts. 

A sharp needle-point tip, 
shown in Fig. 1-e, offers a lot of 
advantages. A sharp tip can pen- 
etrate oxides or insulation easily 
and makes a good connection. 
It's made of stainless steel so it s 
strong, even springy, and easy to 
handle. The sharpness of the 
point digs in and grabs hold of 
the test point, and tends to stick 
and not slide off. One drawback 
is that steel is not the best con- 
ductor, and the sharp point 
means you can't drive too much 
current through it or it will burn 
up. 

A shouldered microtip, shown 
in Fig. 1-d, provides a very small 
needle point, which is ideal for 
piercing insulation, while leav- 
ing only a very small hole. 

The IC leg, shown in Fig. 1-e, is 
a specialty tip, which is a sharp 
needle point protected by insulat- 
ing plastic on each side. As with 
the needle points, it digs in and 
holds in place while the insula- 
tion protects against shorts. This 
is an excellent probe tip for con- 
tacting IC leads. 

Alligator clips, shown in Fig. 1- 
f. are perhaps the most common. 
Nobody likes alligator clips but 
everyone uses them. Because of 
their size, they don't fit into tight 
spaces very well. The clip's weight 
acts as a lever that tends to pull 



BRASS NOTCHED TEST PROBE TIP 
a 



DOG-LEG MICROTIP 
b 



NEEDLE TP 
c 



SHOULDERED MICROTIP 
d 



ICLEG 
e 



I 



INSULATED ALLIGATOR CLIP 



1 



et= 



* 



J-HOOK CLIP 

g 




FINGER CLIP 
ft 



s^x 



SPADE CLIP 
/ 






INSULATED BATTERY CLIP 



/ 



«=an:! 



7 



SLIDE-ON TIPS 
k 



E3KE3c==€ZI^ 



POP JACK 
(CROSS SECTION} 






____ JL.— - 



INSULATED EXTENDABLE TIP 



^-§t 



FIELD REPAIRABLE 

PROBE TIP 

n 

FIG. 1— EACH OF THESE PROBE TIPS 

HAS THEIR OWN distinct advantage when 
used in a specific testing application. All 
of these probe tips should meet most of 
your testing needs. 

itself loose. Their jaws tend to be 
out in the open, contributing to 
inadvertent contact with neigh- 
boring objects, unless they are 
sheathed. Alligator clips come in 
different sizes and, in the right 
applications, they are useful. 



J-hooks, with a spring-loaded 
insulation sheath, can really 
grab a component lead or wire 
and hold on well. That type of pro- 
be tip is shown in Fig. 1-g. They 
come in maxi, mini, and micro 
sizes to adapt to different jobs. 
Gold-plated beryllium-copper al- 
loy makes an excellent contact. 
Don't accept J-hooks of base met- 
al; the savings aren't worth it. 
The spring-loaded sheath is a 
safety factor as well as a mechan- 
ical aid for a good hold. Their ad- 
vantages are obvious. The disad- 
vantage is a slightly higher price 
than straight tips. In very close 
quarters, with tightly spaced 
component leads, J-hooks can 
also present a size problem. 

Pincers, shown in Fig. l-h, 
were designed as a J-hook re- 
placement for use in tighter 
spaces. The "U" shaped tips are 
gold-plated beryllium copper and 
are heat treated to act as a spring. 
They reach around and grab onto 
component leads. Again, a 
spring loaded sheath provides a 
safety advantage and protects 
against shorting to adjacent 
leads. The disadvantage of a pin- 
cers tip is that they are more ex- 
pensive then simpler straight 
tips. 

Spade lugs, shown in Fig. 1-j, 
can be screwed down at a binding 
post, giving you the advantage of 
hands-free operation to turn on 
power, throw your switches and 
make your measurements. In 
specific applications they let you 
hook one or both sides of your 
multimeters and not worry about 
making or keeping contact. 

The battery clip, shown in Fig. 
1-j, was not really designed for 
batteries, but is the common de- 
scriptive name used in industry. 
It lets you grab onto large nuts or 
bolts and holds on strong. 

Probe design 

Many of the tips we have de- 
scribed are available perma- 
nently installed in special pur- 
pose probes. Some are available 
as "slide on" tips (Fig. 1-k), which 
allow a common probe body to be 
interchanged with a variety of 
probe tips and some with "pop- 
jack" connections (Fig, 1-') to 
plug into a common probe body. 

Permanently connected probe 
tips offer advantages to anyone 
who often or repetitively per- 
forms the same test step. You just 



64 






pick up your sturdy probe and do 
the job. The disadvantage is a 
lack of versatility. Either you'll 
have to try and "make-do" with 
the wrong probe occasionally or 
you'll have to buy a number of 
different probes to meet each sit- 
uation, In fact, if you do a large 
amount of testing, having a col- 
lection of probes to meet each sit- 
uation is a wise decision. A 
number of kits of probes selected 
to match various applications are 
available at good prices. 

Slide-on tips give you ver- 
satility You can use a needle- 
sharp tip when you need it, and a 
spade-lug when your need 
changes. They provide big advan- 
tages to anyone that usually 
works with high-voltage equip- 
ment and only occasionally with 
low voltage. 

A particularly useful slide-on 
tip is the insulated extendable tip 
shown in Fig. 1-m. The extenda- 
ble tip is able to get into those 
deep, hard-to-reach spaces with- 
out the worry of shorting of near- 
by components. 

The disadvantage of slide-on 
tips is an outgrowth of the advan- 
tage — the slide-ons can also slide 
off. The pop-jack connection of- 
fers a solution to that problem. It 
allows you to interchange probe 
tips but holds them in place 
tighter. It offers a metal male- 
female connection with a friction 
grab, plus the plastic insulating 
sheaths actually deform and 
create a seal. The pop-jack con- 
nection requires five or more 
pounds of pull to dislodge it, al- 
though if you twist it first, it 
parts easier. It's somewhat like a 
Chinese finger puzzle in its hold- 
ing ability. 

Field repair 

Test probes that are field re- 
pairable have a distinct advan- 
tage over those that are not. Most 
test probes that are non-field re- 
pairable are insert molded, with 
the test leads permanently em- 
bedded in the handle. That meth- 
od of construction can present 
several problems. Most problems 
occur when the lead wire frays 
where it enters the handle. Once 
that happens, the probe must be 
discarded and replaced. 

There can also be a safety haz- 
ard during the manufacturing 
process. A stray wire can some- 
times occur at the tip-and-lead 




POMONA'S MAXI-KIT CONTAINS a wide assortment of probes for the professional DMM 
user. 



junction on the test probe, which 
is usually a crimp. When molded 
into a handle, that stray wire can 
be very close to the surface of the 
probe and, particularly at high 
voltages, presents a serious 
shock hazard. 

At Pomona, the tip-and-lead- 
wire assembly is threaded into a 
hollow handle and the tip is then 
held in place with a screw-down 
chuck. Therefore, it will never 
short through to the probe han- 
dle, and the probe is actually field 
repairable. If the lead wire is 
bent, broken or frayed, you cut it 
off and re-solder the wire to the 
tip, insert it back into the handle 
and chuck it in place. Figure 1-n 
shows a drawing of a field re- 
pairable probe tip. 

Connections 

Connection of the probe to the 
multimeter is through wire and a 
standard banana plug. The wire 
must be properly insulated and 
have a low enough resistance to 
adequately pass signals. Pomona 
test leads use double-insulated, 
18-gauge wire, which more than 
meets all product safety require- 
ments. Various insulating mate- 
rials include: standard PVC. a 
superior PVC that's more flexible, 
or silicone, which is both more 
flexible and much more resistant 
to high temperatures, which is 
usually a problem when using a 
soldering iron. 

There's more to a banana plug 
than you might think. High- 



quality banana springs are made 
of a single piece of heat treated, 
spring quality, beryllium copper. 
Most banana plugs on the mar- 
ket, however, are made of materi- 
als with bus spring retention, 
which makes less dependable 
and less reliable connections. 

Uninsulated banana plugs are 
still available for multimeters, 
but the move is away from them, 
which is all for the better. A bare, 
uninsulated plug swinging loose 
while "hot" is just too dangerous 
to accept. For safety reasons, we 
urge you to use insulated plugs. 

Most users, after they finish 
testing, wrap the leads around 
the meter and put them away un- 
til the next time. That means the 
leads are getting bent at a 90° an- 
gle, banged against a drawer or 
shelf, and eventually tend to 
break or fray. Leads that are 
molded at 90° from the sheathed 
plug will prevent that problem. 

Wrap up 

Multimeter manufacturers 
have a bad reputation for test 
leads. The fact is, your meter 
probably doesn't come with the 
best selection of leads for your 
specific needs. Typically, you 
should plan on investing some 
money on additional test leads. 

Testing can be inherently dan- 
gerous, particularly at higher 
voltages. The closer you get to 
having the correct tool for each 
task, the safer and easier it is to 
perform your testing. R-E 



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D 



way are easily created. 

While the UV photopolyrner nor- 
mally used is both expensive and 
hard to get, a possible hacker sub- 
stitute could be the Merigraph pho- 
topolyrner used for rubber stamps, 
and available by way of Gratham or 
R.A. Stewart. 

A second generation visible light 
photopolyrner is being developed at 
Dupont, and one major system which 
uses these is Quadrax. Advantages 
of the visible photopolyrner include 
its lower viscosity, the ability to use a 
cheaper laser, and (with proper safety 
precautions) being able to see what 
you are doing. Because of the lower 
viscosity, you can also raise the liquid 
level, rather than actually moving 
what you have already produced. 

While these liquid-vat methods do 
work, they are limited in accuracy to 
several mils, are rather costly, and 
end up severely restricting your 
choice of materials. Afresh, different, 
and totally dry approach to desktop 
prototyping gets used by DTM. Here 
a granular powder of certain waxes or 
any of a number of plastics is selec- 



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SYNERGETICS 

Box 809-RE 

Thatcher, AZ 85552 

(602) 428-4073 



tively hardened by an infrared laser in 
a process known as sintering. Sinter- 
ing simply melts the surface of the 
granules so they stick together. 

In addition to being cleaner and 
simpler, you have a wide variety of 
possible material options, including 
real metals. Many powders can be 
reground and recycled, and they are 

NAMES AND NUMBERS 



A! [Ironies 

2300 Zanker Road #D 
San Jose, CA 95131 
(408) 943-9773 
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Castolite 

PO Box 391 
Woodstock, IL 60098 
(815) 338-4670 

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C-Cube 399A West Trimble Road 
San Jose, CA 95131 (408) 944-6300 

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Circuit Design 

1790 Hembree Road 
Alpharetta, GA 30201 
(404) 475-1818 
CIRCLE 304 ON FREE INFORMATION CARD 



Circuit Cellar Ink 

4 Park Street S20 
Vernon, CT 06066 
(203) 875-2751 

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Circuit Works 
303 Potrero Street, Ste 53 
Santa Cruz, CA 95060 
(408) 459-8088 

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GEnie 

401 N. Washington Street 
Rockvillel MD 20850 
(800) 638-9636 

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Hitachi 

2000 Sierra Point Parkway 
Brisbane, CA 94005 
(415) 589-8300 

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Marlin P Jones 

Box 12685 
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(407) 848-8236 
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far cheaper than the photopolymers. 
Let's see, a few loose ends: Other 
approaches to Santa Claus machines 
include photochemical machining of 
thin layers and various other "gas- 
ket" techniques that get bonded to- 
gether to produce composite ob- 
jects. One think tank doing active 
instant prototype development is 

Micro Linear 

2092 Concourse Drive 
San Jose, CA 95131 
(408) 433-5200 

CIRCLE 310 ON FREE INFORMATION CARD 



New Age Industries 

2300 Maryland Road 
Willow Grove, PA 19090 
(215) 657-3151 
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Nickel 

15 Toronto Street, Ste 402 
Toronto, Ont. CAN M5C 2E3 
(416) 362-8850 

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PM Research 

4110 Niles Hill Road 
Wellsville, NY 14895 
(716) 593-3169 

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Schaevitz 

7905 North Route 130 
Pennsauken, NJ 08110 
(609) 662-8000 

CIRCLE 314 ON FREE INFORMATION CARD 






SGS 

1000 East Bell Road 
Phoenix, AZ 85022 
(602) 867-6259 

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Synergetics 

Box 809 

Thatcher, AZ 85552 

(602) 428-4073 

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Texas Instruments 

PO Box 809066 
Dallas, TX 75380 
(800) 232-3200 

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3M Microproducts 
3M Center 
St. Paul, MN 55144 
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4.7K 10uF 



right audio 
left audio a-WA-\{ 
video 



(A) 



7511 



right audio c— WW~jf 
loft audio 
video 



.o-^vW-jfr 



(B) 

right audio 

left audio 

video 

(C) 



o-wHf- 




(inputs) 



t12V 



CTRL1 CTRL2 




(outputs) 



MUTE 



RG. 1— THIS TRIPLE AUDIOVISUAL SWITCHER uses the Hitachi HAA11508 to simulta- 
neously select video and two-channel stereo audio from any one of three sources and 
then route them to one of two selected outputs. 



Batelle, while conventions and semi- 
nars are sometimes done by the 
CAD/CIM Roundtable. One of the 
many sources for traditional CAD/ 
CAM support software appears to be 
Control Automation, 

One thing that's totally obvious to 
me is that the PostScript language 
will play a major role in the future of 
desktop prototyping. Obvious rea- 
sons here are PostScript's nearly 
total device independence, its in- 
credible graphical performance (es- 
pecially for three dimensions), and its 
ability to let your favorite el-cheapo 
word processor completely and total- 
ly blow away virtually any of today's 
costly CAD/CAM packages. 

For our contest this month, just 
add to our Santa Claus machine di- 
alog in some useful way. There will be 
all of the usual Incredible Secret 
Money Machine book prizes going to 
the dozen or so top entries, with an 
all-expense-paid (FOB Thatcher, AZ) 
tinaja quest for two going to the very 
best of all. As usual, please send your 
written entries to me here at 
Synergetics, instead of Radio- 
Electronics. 



An incredible data book 

Certainly one of the most beautiful, 
largest, and most impressive data 
books I've ever run across is the in- 
credible new ASSP for Audio and 
Video Applications data book offered 
by Hitachi. It is crammed to the 
rafters with unique new hacker inte- 
grated circuits. 

Picking a sample more or less at 
random, Fig. 1 shows an audiovisual 
switch using their new HA1 1 508 chip. 
This beast is hard to describe. It 
simultaneously switches one video 
and two stereo audio channels from 
your choice of three sources. As Fig. 
2 shows, there are two separate tri- 
ple outputs, selected per the CTRL1 
and CTRL2 lines. The audio on the 
second triple output can get muted 
using the mufe input. 

This dude is intended to select 
three audiovisual sources inside a TV 
set and route them to two possible 
destinations. But it cries out to be 
used as part of a home- or low-end- 
studio control center or a switching 
bay. 

The quality specs seem fairly im- 
pressive. While a 12-volt supply is 







CTRL1 CTP.L2 


OUT I OUT II 










o o 


A A 










O 1 


A C 




1 1 


B B 




1 o 


B C 













FIG. 2— THE TRUTH TABLE for the triple 
audio switcher. Logic signals on the con- 
trol inputs decide which input gets se- 
lected. An optional mute input turns off 
the audio only on output II. 

recommended, anything from 8 to 13 
volts can be used. All the inputs and 
outputs are supposed to be capaci- 
tor-coupled. Since the switching 
times and all the overlaps are not 
specified, this chip appears to be 
mainly intended for use in static 
switching or source selection. In- 
stead of being applied to chroma-key 
or picture-insertion applications. Nat- 
urally, for any higher-quality switch- 
ing, full double-sided PC boards with 
lots of ground plane are an absolute 
must. 

More on data compression 

There sure was plenty of ongoing 
hacker interest in all of that data-com- 
pression stuff we looked at a few 
months back and in the Hardware 
Hacker lire prints. Much of the action 
today centers on the new Discrete 
Cosine Transform, especially in high- 
resolution color computer and TV 
displays. 

Figure 3 is a bibliography of some 
of the heavier duty papers on the 
DCT. Start out with Chris Ciarcia's 



introductory tutorial in Circuit Cellar 
Ink, and then go on to the fancier stuff 
shown through Interlibrary Loan at 
your local library. 

To compress any video image, indi- 
vidual 8x8 pixel blocks have their 
discrete cosine transform taken, by 
using either hardware or software. 
The result of this transform is a list of 
frequencies and amplitudes. Any 
change so minor that the eye can't 
see it anyway gets replaced with a 
zero, leaving a sparse data set. Put 
another way, what you don't know Cor 
see) won't hurt you. 

The sparse data set then gets fur- 
ther compacted using Huffman or 
similar techniques. The net result is a 
video compression in the 30:1 range 
without causing significant visual 
degradation. 

The reasons for compression is to 
reduce your disk storage time and 
your communication time. Far more 
important, this sort of data compres- 
sion is essential to squash an HDTV 
image down into reasonable band- 
width channels. So knowing and un- 
derstanding video compression is an 
essential part of the new multimedia 
revolution which is combining video 
and computing. 

Two sources of DCT chips include 
C-Cube and SGS, while some useful 
(but very much slower) do-it-yourself 
software routines are shown in the 
Garcia article. 

Digital sine- wave generator 

Hardware hackers interested in 
communications are really getting off 
on a great new integrated circuit from 




A Fast Algorithm for the Discrete Cosine Transform 

C.H. Smith, IEEE Transactions on Communications Sept, 1987 pp 10O4-1G09 

Image Compression for High Speed Network Transmission 
C. Ciracia, Circuit Cellar Ink, Aug/Sep 1990, pp 19-26 

Teleconferencing 

K. Rao. Van Nostrand Retinoid Company, 1985. 

Digital Coding of Waveforms 
N. Jayant, Prentice Hall, 1984. 

A Hew Wave in Applied Mathematics 

B. Cipra, Science 24 Aug 1990. pp 858-859. 

Survey of Adaptive Image Coding Techniques 

A. Habbibi, IEEE Transactions on Communications. Nov 1977, pp 1275-1284. 

Advances in Picture Coding 

H. Mussmann, Proceedings ol the IEEE, April 1985, pp 523-548. 

Progressive Transmission of Gray-Scale and Binary Pictures 

K. Knowlonton, Proceedings ol the IEEE, July I960, pp 885-896. 

Predictive Coding Based on Efficient Motion Estimation 

R. Srinivasan, tEEECont. Communications, May 14 1984, pp 521-526. 

DCT Processing ol NTSC Composite Video Signals 

A. Ploysongsang, IEEE Trans, on Communications, March 1982, pp 462-479. 

FIG. 3— A FEW OF THE RECENT PAPERS on video-image compression and the DCT 
discrete cosine transform. 



Official 1934 

SHORT WAVE 
RADIO MANUAL 




Build 

simple 

performance old 

lime shortwave radiosl 

All of the secrets are 
here: the circuit diagrams, 
parts layout, coil specifications, con- 
struction details, operation hints, and 
much more! 

This is a compilation of shortwave 
construction articles from "Short Wave 
Craft" magazines published in the 20's & 
30's, It's wall-to-wall "how-to." 

Included are circuit diagrams, photo- 
graphs, and design secrets of all short- 
wave receivers being manufactured in 
1934 including some of the most fa- 
mous: SW-3. the SW-5 "Thrill Box", the 
deForest KR- 1 , the Hammurland 
"Comet Pro", and many more. 

Also included is a new chapter show- 
ing how you can use transistors to re- 
place hard-to-find vacuum tubes. You'll 
even see the circuit that was lashed 
together on a table top one night using 
junk box parts, a hair curler and alliga- 
tor clips. Attached to an an- 
tenna strung across the base- 
ment ceiling and a 9 volt bat- 
tery, signals started popping 
in like crazy. In a couple of 
minutes an urgent message 
from a ship's captain off Se- 
attle over 1500 miles away 
was heard asking for a naviga- 
tor to help him through shallow waterl 

These small regenerative receivers 
are extremely simple, but do they ever 
perform! This is a must book for the 
experimenter, the survivallst who is 
concerned about basic communlcaUon. 
shortwave listeners, ham radio opera- 
tors who collect old receivers, and just 
about anyone interested in old-time 
radio. 

Great book! Fun to read! One of the 
best old-time radio books to turn up in 
years. Heavily illustrated! Order a copy 
todayl 8 1/2x11 paperback 260 pages 
only"$ 15.70 postpaid! 

r Lindsay Publications 1 

Box 583-WA8 Manteno IL 60950 




I I Send a copy of Short Wave £ 
^Manual. Enclosed is $1! 



■Radio 
15.70. 

Chk, MC, Visa. Send a free cata- 
log of other books. 



1 Nsrni- 






1 


1 






1 


^Ity 


St 


Zip 


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73 



y 
z 
o 

F 
u 

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_i 

LU 

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2 



Micro Linear. This is their ML2035 
Programmable Sine-wave Generator. 
Cleverly disguised as an eight-pin 
mini-DIP. this new chip is an $8, full 
performance, 16-bit digital sine-wave 
generator. It has a 21 -bit phase ac- 
cumulator and a 9-bit sine lookup ta- 
ble built into it! 

The device can easily produce any 
sine wave from 1 Hz to 25 kHz in 1 -Hz 
steps, and its serial interface mates 
beautifully with virtually any computer 
or microcontroller. Figure 4 shows the 
extremely simple circuit. A split sup- 
ply of +5 and -5 volts is needed. 
The output frequency resolution will 
be: 

f OUT = fxTAl7 8 ' 388 ' 608 

Thus, you would use the 8.388608- 
MHz crystal to get a 1-Hz resolution. 
Or you could apply any external fre- 
quency up to 12 MHz. 

Your output sine-wave frequency is 
determined by the 16-bit digital word 
you last selected. For instance, a dig- 
ital "1" would get you 1 Hz, while a 
"5623" Cor a hex $15F7) will get you 
5,623 kHz, Your output is a clean and 
low-distortion sine wave of around 1 2- 
volts peak-to-peak. 

In order to save on package pins, 
your digital control word is entered 
serially. There are three pins involved. 
The serial input data CSID) pin accepts 
one data bit at a time, the least signifi- 
cant bit first. The SCK or serial clock 
accepts each new data bit on its ris- 
ing edge. Finally, the LAT or laich pin 
stores the input serial data stream on 
its falling edge. 

This should interface beautifully 
with the game-paddle port of an Ap- 
ple lie, or anywhere else you have 
three I/O lines available from a com- 
puter or microcontroller. There's also 
an ML2036 in a larger package with 
some extra features at slightly higher 
cost. 

One obvious tip: You do enter the 
frequency in binary or in hex, and not 
in decimal! Don't laugh. That's a very 
common hacker mistake. 

As a second contest for this 
month, just tell me something dif- 
ferent you would do with this new 
ultra-cheap, ultra-simple, and ultra- 
precise digital sine-wave generator. 

New tech literature 

Schaevitz has a free Handbook of 
Measurement and Control that gives 
the fundamentals of LVDT position- 
ing sensors. From SGS, there's a 



SANTA CLAUS MACHINE 
RESOURCES 



Batelle 

505 King Avenue 
Columbus, OH 43201 
(614) 424-7782 
CIRCLE 319 ON FREE INFORMATION CARD 



CAD/COM Roundtable 

1050 Commonwealth Avenue 
Boston, MA 02215 
(617) 232-8080 
CIRCLE 320 ON FREE INFORMATION CARD 



Control Automation 

2350 Commerce Park Dr NE, #4 
Palm Bay, FL 32905 
(407) 676-3222 
CIRCLE 321 ON FREE INFORMATION CARD 



DTM 

1611 Headway Circle B2 
Austin, TX 78754 
(512) 339-2922 

CIRCLE 322 ON FREE INFORMATION CARD 



DuPont 

1007 Market Street 
Wilmington, DE 19898 
(302) 774-1000 

CIRCLE 323 ON FREE INFORMATION CARD 



Freeman Supply 

1246 West 70th Street 
Cleveland, OH 44102 
(800) 321-8511 

CIRCLE 324 ON FREE INFORMATION CARD 



Grantham/Polly-Stamp 

418 Central Avenue NE 
East Grand Forks, Ml 56721 
(218) 773-0331 

CIRCLE 325 ON FREE INFORMATION CARD 



Industrial Education 

1895 Crooks Road S135 

Troy, Ml 48084 

(313) 649-4900 
CIRCLE 326 ON FREE INFORMATION CARD 



new data book on Protection Devices 
that includes surge and transient sup- 
pressors. 

Texas Instruments has a new and 
free linear products sample packet 
on their Excalibur series of JFET oper- 
ational amplifiers. 

Two great surplus flyers include 
Alltronics. who are big on powerful 
magnets and computerized hamsters 
(their dead ones are cheaper); and 



Light Machines 

669 East Industrial Drive 
Manchester, NH 03103 
(603) 625-8600 

CIRCLE 327 ON FREE INFORMATION CARD 



masterCAM 

2101 Jericho Turnpike 
New Hyde Park, NY 11 040 
(516) 328-3970 

CIRCLE 328 ON FREE INFORMATION CARD 



Merigraph Hercules 
300 East Shuman, Ste 260 
Naperville, IL 60566 
(800) 323-1832 
CIRCLE 329 ON FREE INFORMATION CARO 



Quadrax 

300 High Point Avenue 
Portsmouth, Rl 02871 
(401) 683-6600 

CIRCLE 330 ON FREE INFORMATION CARD 



Roland Digital 

7200 Dominion Circle 
Los Angeles, CA 90040 
(213) 685-5141 

CIRCLE 331 ON FREE INFORMATION CARD 



School Shop 

Box 8623 

Ann Arbor, Ml 48107 

(313) 769-1211 

CIRCLE 332 ON FREE INFORMATION CARD 



RA Stewart 

641 South Palm, Unit H 
La Habra, CA 90631 
(213) 690-4445 

CIRCLE 333 ON FREE INFORMATION CARD 



3-D Systems 

26081 Avenue Hall 
Valencia, CA 91355 
(805) 295-5600 

CIRCLE 334 ON FREE INFORMATION CARD 



Marlin Jones, who has some new tilt- 
angle sensors, parabolic mirrors. 
LCD displays, clutches, and reg- 
ulators. 

Our featured free trade journals for 
this month include Circuit Design on 
printed-circuit layout techniques, and 
Nickel, devoted to stainless steel and 
all other nickel applications. 

Still at the same old stall after all 
these years, the Castolite people of- 



74 



8.398 MHz Crystal 



SERIAL DATA CLOCK _T O- 




ANALOG 
-O OUTPUT 
SINEWAVE 



ML2035 



SERIAL DATA IN J~l o- 



DATA LATCH "L O- 



FIG. 4— A DECEPTIVELY SIMPLE DIGITAL SINE-WAVE GENERATOR. This $8 chip does a 
full 21-bit phase addition and a 512-level table lookup for an outstanding output quality. 
Resolution is 1 Hz over a 1-Hz to 25-kHz range! 



fer all sorts of castable resins and 
mold products. One good way to get 
started with the castable resins is to 
pick up their$75 product sample and 
evaluation kit. 

The Circuit Works people have an 
interesting conductive pen that 
writes in silver ink. The main use for 
this unusual gadget is for printed-cir- 
cuit-board repairs. 

For some additional mechanical 
stuff, 3M has an interesting brochure 
on microcapsule technology, while 
free plastic-tubing samples are newly 
available through NewAge Industries. 
And PM Research has a fine catalog 
on steam-engine kits. 

Turning to my own stuff, I have 
combined my seven top hacking 
books into a Lancaster Library at a 



very special price. These include the 
TTL Cookbook, CMOS Cookbook, 
Active Filter Cookbook, Micro Cook- 
book I, Micro Cookbook II, Hardware 
Hacker II, and, of course, The Incredi- 
ble Secret Money Machine. 

Finally, I do have a new and free 
mailer for you which includes dozens 
of insider hardware-hacking secret 
sources. Write or call for info. 

Our usual reminder here that most 
of the items mentioned appear either 
in the Names and Numbers or in the 
Santa Claus Machines sidebar. 

As always, this is your column and 
you can get technical help and off- 
the-wall networking per that Weed 
Help?box. The best calling times are 
weekdays 8—5, Mountain Standard 
Time. Let's hear from you. R-E 



Try the 

MziEntmniESi 

bulletin board system 



(RE-BBS) 
516-293-2283 



The more you use it the more 
useful it becomes. 

We support 300 and 1200 baud 
operation. 

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75 






AUDIO UPDATE 



Amplifier Transfer Functions: A Strange Audio Controversy 



LARRY KLEIN 




w 
o 

z 
o 

cc 

o 



g 

5 
< 



y IEEE dictionary defines 
transfer function as "a 
mathematical, graphic, or 
tabular statement of the influence 
that a system or element has on a 
signal or action compared at input 
and output terminals..." The some- 
what stilted language refers essen- 
tially to whatever differences occur 
between the input and output signals 
of a circuit. It may seem strange that 
an Innocuous technical term Hike 
"transfer function" could in another 
guise excite such passions in the au- 
diophile community. It all began, as 
have several other audio controver- 
sies in the past decade, with the work 
of Bob Carver, former president of 
Phase Linear, and presently the presi- 
dent and chief engineer of the Carver 
Corporation. 

The Carver Corporation 

When Carver founded the compa- 
ny that bears his name, he produced 
two products that both excited audio 
consumers and rattled a few cages. 
The first to hit the market was a 
"sonic holography" preamplifier that 
provided an enormous extension of 
the sonic sound stage far beyond nor- 
mal speaker spacing. In fact, on cer- 
tain program material, the effect is as 
though two invisible side-wall speak- 
ers have been switched in. The holo- 
graphic illusion is achieved by 
electronically nullifying the interaural 
crosstalk that occurs with conven- 
tional speaker setups. Normally, the 
sound from the right speaker reaches 
your left ear and the sound from the 
left reaches your right ear: the Carver 
circuit injects some out-of-phase left 
signal into the right channel and vice 
versa, thus electronically canceling, 
when you are properly located, the 
acoustic "leakage" between both 
channels. 

Carver's sonic holograph promp- 
ted a host of "me-too" products, and 
variations on the idea are still found in 
the products of some companies. 
Not surprisingly, purist audiophiles 



complained in letters to audio maga- 
zines that Carver was illegitimately 
monkeying with the integrity of the 
audio signal, that the effects 
achieved were far from realistic, and 
that the recommended listener posi- 
tion was unduly restrictive. However, 
buyers of the Carver sonic-holograph 
preamp simply enjoyed its effect, un- 
troubled by the objections of the pu- 
rists. 



£_ 



MUSIC SIGNAL 
A. 



MODIFIED 
AMP 



'ft 



REFERENCE 
AMP 



(-) 



A 



II 




NULL 
SPKR 



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NORMAL 
SPKR 



Fig. 1. CONNECTION FOR COMPARING 
one channel of a reference amplifier to 
one channel of the modified amp. The nor- 
mal speakers, whose purpose is to pro- 
vide a typical load, are placed out of 
earshot. The null speaker plays only the 
difference between the two channels. 
Theoretically, two identical channels will 
produce no sound from the null speaker. A 
meter connected across the null speaker 
has revealed nulls as low as - 70 dB. 



The Carver challenge 

Bob Carver's next project was the 
M-400 "magnetic-field" amplifier. 
Truly a revolutionary product, it was a 
200-watt-per-channel amplifier em- 
bodied in a 7-inch cube weighing a 
mere 10 pounds. Once again, au- 
diophiles who tended to judge an am- 
plifier's quality by its cost — and the 
severity of the hernia you got trying to 
lift it — were outraged. Obviously, 
there had to be something wrong with 



the M-400's sound that did not show 
up in conventional testing, yet was 
surely audible to anyone with ears 
golden enough to hear it. 

Bob Carver told me several times 
during that period how distressed he 
was by the self-selected audio es- 
thetes who felt that he was, at best, a 
designer of mid-fi equipment. Carver 
set out to prove them wrong. He de- 
vised and demonstrated a nullifica- 
tion circuit (not unlike the Hafler 
circuit discussed in these pages sev- 
eral years ago) that would null out all 
similarities in the signal between any 
two amplifier channels leaving only 
whatever differences might exist in 
phase shift, frequency response, dis- 
tortion, and/or noise to be heard. 

I attended at least two of Carver's 
demonstrations and came away con- 
vinced that his amplifier was essen- 
tially perfect in respect to absence of 
any audible problems. In truth, I was 
not terribly surprised by Carver's test 
results since I believe that almost any 
well-designed amplifier when oper- 
ated with a reasonable speaker load 
and within its power rating will sound 
like any other amplifier also operated 
under the same conditions. (That is 
also Carver's view, but he hesitates 
to propagate it for fear of further al- 
ienating the irrational self-appointed 
audio elite.) In any case, Carver made 
his point among those willing to be 
convinced. But Carver's test con- 
vinced none of the audio fundamen- 
talists whose ultimate faith resides in 
what they think they hear under their 
own essentially uncontrolled listening 
conditions. 

For this group, only prolonged lis- 
tening to one amplifier and then the 
other will allow proper evaluations to 
be made. Anyone who has attempted 
to make scientific subjective assess- 
ments in any product area knows of 
the pitfalls of such a procedure, but 
nevertheless, that is the preferred au- 
diophile evaluation technique. 

Okay, thought Carver, let's ap- 
proach the problem from a different 



76 



direction. He issued a challenge to 
the editors of Stereophile magazine: 
You pick out an esteemed high-end 
power amplifier — tube or tran- 
sistor — and I will duplicate its sound 
by minor modifications of one of my 
current $700 magnetic-field ampli- 
fiers. Carver flew out to Stereophile's 
Santa Fe, NM, offices and set up his 
equipment in a nearby motel, and 
Stereophile brought over a massive 
$5,000 tube amplifier to serve as the 
reference. Several days later, Bob 
emerged from his instrument- and 
parts-cluttered motel room with the 
modified Carver amplifier whose 
sound he claimed exactly matched 
that of Stereophile's audiophile tube 
amplifier. 

Here comes the surprising part: 
After hours of comparison listening, 
the flabbergasted editors of 
Stereophile reluctantly agreed that 
Carver had accomplished just what 
he claimed he would. The sound of 
the two amplifiers was indistinguish- 
able even with the "best available" 
associated equipment and speakers! 
The implications of what Carver had 
done was not lost on those who had 
participated in the event. How could 
Carver's amplifier duplicate the 
sound of the reference, without the 
use of gold-plated connectors and 
circuit boards, oxygen-free copper 
wire, capacitors with special di- 
electrics, and metal-film resistors, 
and all the other magical elements — 
including tubes — that are found in au- 
diophile amplifiers? Could it be, as 
Carver claimed, that the only thing 
necessary was to get the proper 
transfer function? 

Now for the unsurprising part. 
Upon reflection, reconsideration, and 
relistening to the original modified 
Carver amp plus other samples that 
Carver had modified similarly, 
Stereophile's staff decided that the 
amplifiers really didn't sound alike 
after all. How could they, when the 
basic premise of the magazine (and 
high-end audio) suggests the exis- 
tence of subtle, mysterious audible dif- 
ferences that differentiate audiophile 
equipment from that produced by the 
"mass merchandisers" such as Car- 
ver. You wipe out those differences 
and you obviously wipe out the justi- 
fication for overpriced and over- 
designed high-end audio equipment. 
I asked Bob exactly what he does 
to match the sound of two amplifiers. 
Essentially, fie said, the differences 



he's eliminating are all in the spectral 
domain. However, that involves more 
than simply matching the frequency- 
response characteristics of two am- 
plifiers. Every amplifier has a charac- 
teristic complex input and output 
impedance that causes small fre- 
quency response variations when 
driving various speakers and when 
being driven by various input compo- 
nents. Matching the sound of two 
amplifiers consists essentially of 
matching those impedance charac- 
teristics. It isn't necessary to work 
out the reasons for the impedance 
characteristics of the reference amp, 
only to duplicate them. 



Postscript 

I thought that Carver's approach to 
amplifier matching would make an in- 
teresting story and I offered it to 
Audio magazine. The editor, whom 
I've known for years, turned me down 
flat. Why? His belief system, like 
those of the editors of Stereophile, 
would not permit him to accept that 
Carver's feat was possible. And a 
final note: Since Stereophile re- 
canted, they have, in Carver's view, 
constantly attacked his products in 
editorial comments and reviews. That 
has led indirectly to a series of legal 
claims and counterclaims, which, are 
now being worked out in court. R-E 




'.'/ think he hives 
me. . - He let me lemh 

his stereo. " 



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Let's keep our DTMF generator circuit as simple and 
as elegant as possible. 



ROBERT GROSSBLATT 



Just about everyone who owns 
a computer has had to deal 
with plug-in cards at one time 
oranother. Back in the old days, there 
were no such things as ASIC's Cap- 
plication specific integrated circuits), 
and it was even rare to see a board 
with PAL's (programmable logic ar- 
rays) on it. Most of the board design- 
ers and manufacturers produced 
products that were constructed en- 
tirely around recognizable hardware. 
That usually meant that you'd see lots 
of 74-series logic on the board with 
an occasional EPROM Ca 2708) to 
handle unusual gating requirements, 
data tables, and so on. 
Things aren't like that any more. 
Modern boards, and most modern 
electronic products, are now built 
around custom silicon since the 
failure rate is a lot lower and the cost 
of production is less as well. This is 
good for the consumer since the 
products are a lot more reliable and 
less expensive. A VGA card is an 
extremely complex circuit but you'll 
find the parts count to be minimal. 



The down side of all this is that it's 
next to impossible to fix any of the 
newer boards. You not only can't get 
the ASIC's that form the heart of the 
design but, even if you could, very few 
(if any) of such newer boards are de- 
livered with a schematic and circuit 
description. 

The reason I'm mentioning this is 
because the state of board design 
has led a lot of people to assume that 
discrete design is a thing of the past. 
That's just not true since even the 
most complex and custom designed 
boards start out in life as a load of 
discrete circuitry built around the 
same MSI (medium scale integration) 
stuff that, once upon a time, also ex- 
isted on the final products. 

The major contribution of the de- 
velopment of ASIC's has to do with 
economy, not electronics. The same 
sort of argument applies to compo- 
nent density. Not every product made 
to work with a computer has to be 
complex. As a matter of fact, 
Grossblatt's Fourteenth Law— Keep 
it Simple — tells you that things 



should be only as complicated as 
they have to be to get the job done. 
Not only that, but the more time you 
spend doing electronics, the more 
you'll appreciate the advantages you 
get when you keep things as simple 
as possible. If the word "simple'' 
bothers you, think of it as being "ele- 
gant" instead. 

The circuitry for the controller 
we're building doesn't have to be any 
more complex than is required by the 
job it's designed to do. We're building 
a telephone dialer and, although 
there are certainly an infinite number 
of things we can have it do, all we're 
looking for in the beginning is the abil- 
ity to generate DTMF tones — and 
we've already talked about all the sil- 
icon needed to do that. 

The DTMF generator we're de- 
signing is basically a two-chip circuit 
since most of the work is done by the 
5088 that generates the tones. Al- 
though tone-generator chips are a far 
cry from an ASIC, it would take an 
impressive amount of silicon to re- 
place them. 



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FIG. 1— THIS CIRCUIT COMBINES the latch layout we already developed with the 5068. 
With a bit of simple software, it will generate DTMF tones under keyboard or program 
control. 



78 



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We've already laid out most of the 
circuit we need to implement our de- 
sign, and all we have left to do (from 
the point of view of hardware) is to put 
it all together. The circuit shown in 
Fig. 1 combines the latch layout we 
already developed with the 5088 and, 
when we add a bit of simple software, 
will generate DTfvlF tones under key- 
board or program control. 

The first four data lines from the 
parallel port are used to talk to the 
5088 through the latch. Even though 
the latch control of the 373 is brought 
out to the connector going to the 
parallel port, we can ignore it for a 
while by tying the enable line to 
ground. You can do this with a jumper 
on the breadboard or. if you want, 
seven of the pins on the parallel-port 
connector can be tied to ground. 
There were originally eight ground 
pins but remember that we modified 
one of them CI suggested pin 25) so 
that it would carry five volts and make 
it easier to power the circuit we're 
building. 

The only thing new in the sche- 
matic is the colorburst crystal added 
across pins 6 and 7 of the 5088, That 
is the only component we have to add 
to the circuit to make it work. The 
jumper shown hanging off pin 3 al- 
lows you to tie the pin either high or 
low. Making it high will enable the chip 
to generate DTMF, and making it low 
will cause the IC to generate the highl- 
and low-group tones separately. The 
selection of high or low group is made 



with the jumper at pin 4. If you tie pin 4 
low, the chip will generate the low- 
group tones, and tying it high will gen- 
erate the high-group tones. If you 
make pin 3 high by connecting it to 
+ V, the chip generates DTMF re- 
gardless of the connection made at 
pin 4. 

Although the circuit shown in Fig. 1 
still has to have things added to it if 
you want to do practical things with it 
(connect it to the phone line, control a 
telephone, etc.), that doesn't mean it 
has no use at all. Since it's generating 
real DTMF. the output of the 5088 
can be connected to any circuit that 
gets driven or controlled by DTMF 
tones. We'll talk about additional 
hardware later on but, for the mo- 
ment, it's time to turn to the software 
part of the design. 

Since this is the most basic hard- 
ware design we'll have for the circuit 



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(other refinements will come later), it 
stands to reason that the software is 
going to be simple as well. ..at least at 
this stage of the game. 

All we're interested in at the mo- 
ment is writing a few lines of code to 
tell us whether the hardware is work- 
ing or not. Since I want to keep things 
as broadbased as possible, I'll write 
the software in Basic. 

Although you're free to drive the 
latch with any four of the many outgo- 
ing lines on the addresses that make 
up the parallel port, we can be nice 
and logical and use the data port. If 
the port you're working with is LPT1. 
the data port is at 3F3CH or 956 deci- 
mal. Things aren't as clear with the 
other parallel ports. (LPT2, LPT3, 
etc.), since the addresses aren't 
fixed. LPT2, for example, can have its 
base address at 378h, 278h. or 
elsewhere. 

As I talk about software, I'll be re- 
ferring to LPT1. If you're using a dif- 
ferent port, you'll have to substitute 
the proper addresses yourself. The 
hardware is set to pay attention to 
only the lower four bits of the data 
port and, as you can see from Table 1 , 
the bit combination sent to the port 
will determine which one of the 
DTMF tones we generate. 

The actual code we need to exer- 
cise the hardware is simple stuff 
since it's nothing more than a single 
OUT instruction. All we want to do is 
send the data shown in Table 1 on the 
(Continued on page 90) 



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79 



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home or office 

• ROLL YOUR 
OWN RADIO 

Build a crystal radio using only home- 
made parts 



SUPER-SIMPLE 
FREQUENCY COUNTER 

Build it as a stand-alone unit or as an 
add-on for other projects 

BUILD A SHORTWAVE 
PRESELECTOR 

Improve the performance of your re- 
ceiver with these easy projects 




And there is more! 



PRODUCT REVIEWS— Casio 

co lor- LCD pocket TV, Nikon Hi-8 
camcorder, Videonics color equal- 
izer. Sams Photofacts, and more. 

OX LISTENING — Business news 
on shortwave radio. 

COMPUTER BITS— Do comput- 
ers interfere with creativity? 



CIRCUIT CIRCUS— Build a "time- 
out" circuit, a two-input door-bell an- 
nunciator, and a simple speak- 
erphone. 

HAM RADIO — Adjusting antennas 
with an RF dip meter. 

ANTIQUE RADIO— Building your 
own radio-tube tester. 



IC SPOTLIGHT 



continued from page 66 



O 

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PICK UP lU pUittl LlCtllUJlll> AT YOUR FAVORITE 
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Chips of a feather... 

...come in sets together. Thanks to 
LSI Logic, you can now build an entire 
core of a workstation which is binary 
compatible with the SPARCstation-1 , 
a reduced instruction-set computer 
(RISO-based workstation made by 
Sun Microsystems, from a single 7- 
chip set. All that's needed to com- 
plete the system are peripherals and 
their controllers, boot PROM's, and 
the main and cache memories. Figure 
1 shows a block diagram of the 7-chip 
system. 

The chip set includes an integer 
processor, a floating-point processor, 
memory-management, direct memo- 
ry access CDMA), standard I/O and 
bus controllers, and cache control- 
lers and tags. At the heart of the sys- 
tem are two processors, the L64811 
and L648T5. The L6481 1 RISC-based 
integer unit CIU) has 136 general-pur- 
pose registers organized into eight- 
register windows. It has a four-stage 
pipeline, and can execute most com- 
mands in a single cycle, thus giving it 
18-29 MIPS of performance. It also 
has two coprocessor interfaces, one 
for a user-definable coprocessor, and 
the other for the L64814 FPU. The 
L64814 performs double-precision 
operations at speeds of up to 6 
megaFLOPS at 40 MHz. The FPU's 
controller section synchronizes the 
FPU with the IU and provides addi- 
tional floating-point hardware sup- 
port. 

The L64815 is a cache memory- 
management controller that imple- 
ments the SPARC Reference memo- 
ry management unit's CMMU's) 
virtual address translation mecha- 
nism as specified by Sun and AT&T 
Using a 64-entry translation look- 
aside buffer (TLB), this MMU imple- 
mentation will be used in all future 
Sun workstations, and will support 
the next release of SunOS and UNIX 
System V, Release 4. 

The L64815 also provides cache 
tagging, with the tag memory inte- 
grated into the IC. There are 2048 
usable tags, giving the designer great 
flexibility in designing the memory 
subsystem. It can be made up of 32-, 
64-. 128-, or 256-kilobytes of com- 
bined data and instruction cache 
memory, with line sizes of either 32. 
64 or 128 bytes. 



80 









APPLICATIONS PROGRAMS 










HARD 


CPU 




FLASH 
MEMORY 


EXECUTABLES AND OVERLAYS 
PROGRAM VARIABLES 


HEAPS, 

STACKS 

VARIABLES 




RAM 


TEMPORARY DATA 






DISK 








r- _j 

















FIG. 2— FLASH MEMORY CAN BE used to store entire programs from disk. RAM is still 
needed, though, to store program heaps, stacks, variables, and other data that must 
change randomly throughout the program's run time. 



The memory manager connects to 
the memory through a high-speed 
"M bus," which passes data to and 
from memory at a blazing 320-rnega- 
bytes per second at 40 MHz. Pe- 
ripheral controllers connect to both 
each other, as well as to the pro- 
cessors and memory through the 
Sun-developed "S bus," which push- 
es data through at 100-megabytes 
per second at 25 MHz. 

The L64852 Mbus-to-Sbus con- 
troller is used to control the two 
buses. That IC has five primary func- 
tions: 1. to act as an Mbus arbiter, 2. 
to act as an Sbus controller, 3. it is an 
Mbus and an Sbus master/slave con- 
troller and data buffer, 4, it provides 
Mbus-to-Sbus protocol conversion, 
and 5. it is used for I/O memory man- 
agement. 

The set is rounded off by a main- 
memory controller, the L64850, a 
Standard I/O controller, the L64851 
and a DMA controller, the L64853, 
which connects to a small-computer 
systems interface (SCSI) and local- 
area network CLAN) controller. Two 
versions of the system are the Spar- 
KIT-25 and the SparKIT-40, which 
provide 18 and 29 MIPS of perfor- 
mance, respectively. Both chip sets 
are used in LSI Logic's proprietary 
0.7-micron HCMOS process. The 
SparKIT-25 is $1,327.00 per kit. in 
1000-unit quantities. 

Memory in a flash 

As new types of microprocessors 
hit the scene, so too must new types 
of microcomputer memory to sup- 
port them. One such new type of 
memory is the flash memory from In- 
tel. Touted as non-volatile RAM. 
these devices are more similar to a 
higher-speed, lower-cost EEPROM's. 

The chips are non-volatile in nature 



and data can be read randomly, but 
that's where the RAM similarity ends. 
Writing and erasing has to be done to 
the whole chip at once. Erasing an 
entire 1 -megabit chip takes one sec- 
ond, while writing data to that whole 
chip takes four seconds. 

A possible application of flash 
memory is shown in Fig. 2. Flash 
memory can be used to store entire 
programs from disk, which the CPU 
runs as if it were from RAM. RAM is 
still needed to store program heaps, 
stacks and variables and other data 
that must change randomly while the 
program is running. 

Since they can't be written to ran- 
domly, flash memories will not likely 
replace all of the RAM in any sys- 
tems. They can be of great use, how- 
ever, in reducing PC-board real estate 
in workstations that need a lot of 
memory to store running applica- 
tions. Such applications will, of 
course, have to be rewritten to map 
temporary memory contents into 
RAM and keep executable and over- 
lay files in flash. Of course, their first 
application will likely be as nonvolatile 
backup memory that will come into 
play in the event of a power failure or 
as storage in laptop computer sys- 
tems. 

The typical cost of Intel's flash 
memory chips varies according to the 
memory density. The price for a 1- 
megabit 28F010 is $18.70, and is 
sold in a DIP package. A 2-megabit 
28F020 costs $34.80 in a DIP pack- 
age, and $45.20 in a thin small-out- 
line package CTSOP) used in surface- 
mount technology CSMT) designs. All 
prices are for 10,000 unit quantities. 
We'll see you next month for a look at 
the all but forgotten world of analog 
multiplier IC's and the role they play in 
phase-locked loops. R-E 




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:M^^H»Ulil?l- 




Electronics Workbench, an electronics lab simulation program 



JEFF HOLTZMAH 



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You can throw away your sol- 
derless breadboard and spare 
parts junk box. Electronics 
Workbench CEWB) provides a full 
graphical simulation of an electronics 
lab, complete with breadboard, parts 
bin, and test instruments. The pro- 
gram allows you to build a schematic 
diagram of a circuit, simulate its oper- 
ation, and display its output on a vari- 
ety of test instruments, including a 
digital-volt meter CDVM), scope, 
eight-channel logic analyzer, Bode 
plotter, and so on. Building a circuit is 
simple and intuitive. Documenting 
your results is simple as well because 
the program provides nicely format- 
ted printouts of everything, including 
the schematic, instrument readings, 
and parts list. 

EWB comes on four floppy disks 
and requires about 1 megabyte of 
disk space, but it can run on a dual- 
floppy machine. You need at least 
512K of RAM, a graphics monitor 
(Hercules, CGA. EGA, MCGA, or 
VGA), and a mouse. No extra memo- 
ry or math coprocessor is required or 
used. Unfortunately, the current ver- 
sion of EWB costs $650, but the 
company, Interactive Image Tech- 
nologies of Ontario, Canada, is work- 
ing on a new "personal" version that 
should be priced for student and hob- 
byist use. 

EWB actually consists of separate 
analog and digital modules; you can- 
not build "mixed" circuits. The digital 
screen is shown in Fig. 1. When you 
first start the program, the central 
area is blank: the figure shows a sim- 
ple divide-by-two circuit. The screen 
is divided into three major areas. 
Across the top is a row of test instru- 
ments on the left, and program-con- 
trol menus and icons on the right. 
Down the right side is the parts bin. 
To add a part to a circuit, you move it 
from the parts bin, place it where you 
want it, and connect it to other com- 
ponents. Unlike a real parts bin, there 
is an unlimited number of each com- 
ponent. The default parts bin includes 




FIG. 1— THE ELECTRONICS WORKBENCH GRAPHICALLY simulates an electronics lab. 
In the digital module, you choose the components from a parts bin, build a schematic 
diagram on a breadboard, simulate its operation and display the output on a variety of test 
instruments. 



items such as and, nand, oh, nor, xor. 
and not gates, as well as D, RS, and 
JK flip-flops. In addition, there is a 
half-adder, seven-segment LED dis- 
play, discrete LED's, a ground, and 
+ 5-volt sources. 

You can even create your own 
parts using EWB's macro feature. For 
example, you might combine six hex- 
inverters and call the result a 7404. 
You can load and save parts bins in- 
dependently of your circuits. You can 



ITEMS DISCUSSED 

• Electronics Workbench ($650), In- 
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Ontario, Canada M5V 2P2. (416) 
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CIRCLE 42 ON FREE INFORMATION CARD 



give each part a label, and in the ana- 
log module, a value. Display of labels 
and values is normally disabled, but 
you can tum either or both on. The 
designations, however, often obscure 
the parts. 

In Fig. 1 , note that the k input is 
connected to + 5 volts, the output 
is connected to the j input, and the 
clh and pr inputs are grounded. Driv- 
ing the Clk input is a pulse generator, 
with a zoomed-out view appearing in 
the lower left corner of the screen. 
The clk output of the pulse generator 
drives the test circuit. Note, however, 
that the generator actually has eight 
outputs, and you can define 16-bit 
patterns to drive those outputs. Defi- 
ning the bit patterns is somewhat 
awkward because you have to type in 
Ts and 0's; it would be easier and 
more logical simply to toggle a bit 
each time you clicked on it with the 
mouse. However, you can load and 
save bit patterns to disk files. The 
pulse generator has three different 



86 



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modes: 1 ) single step, in which one bit 
is delivered each time you click on the 
step button; 2) burst, in which all 16 
bits are delivered sequentially; and 3) 
cycle, in which all the bits are output 
repetitively. 

The output of the flip-flop is con- 
nected to a logic analyzer, a zoomed- 
out view appears behind and the 
pulse generator. The pulse generator 
drives channel one (shown in the up- 
per trace) of the logic analyzer, the 
output of the flip-flop drives channel 
two (lower trace). Logic-analyzer op- 
tions include positive, negative, and 
external triggering, and a display of 
the waveform, either as received or 
after receiving a pattern. 

On-line Kelp 

EWB includes a top-notch on-line 
hypertext-based help system. Note 
that the text box of Fig. 1 describes 
the "JK Flip-flop". To get that type of 
description, you simply highlight a 
component and press F1 . In that text 
box, the word theory is highlighted. 
You can click on it to receive a more- 
detailed description. It's hard to see 
in the figure, but "RS flip-flop" is high- 
lighted as well. You can also click on it 
for comparative information. The help 
texts are brief summaries, so they are 
not really substitutes for full textbook 
explanations. However, the manual 
includes complete instructions for 
modifying and adding to the built-in 



help texts. 

Moving from right to left, the icons 
in the upper right corner of the screen 
allow you to scroll through the parts 
bin, scroll the screen, start simula- 
tion, and drop down a command 
menu. The command menu allows 
you to get help; cut, copy, move, and 
rotate components; set preferences; 
and load, save, and print files. All 



common laser and dot-matrix printers 
are supported. 

Moving from left to right, the icons 
in the upper left corner represent test 
instruments. First is a DVM, then the 
pulse generator, then the logic ana- 
lyzer, then the "truth table." The lat- 
ter converts digital circuits among 
three different representations; a cir- 
cuit diagram, a truth table, and a 




FIG. 2— EWB'S ANALOG MODULE IS SIMILAR to the digital module except there are more 
components and different test instruments. Meter characteristics are ideal, but you can 
change their impedances to simulate real-world operation. 



o 

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CD 



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87 





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Boolean expression. You can create 
a circuit by filling in a truth table. On 
the other hand, you could attach it to 
a working circuit, get a truth table, 
and verify your design. EWB uses the 
Quine-McCluskey synthesis al- 
gorithm when going from a truth table 
to a Boolean expression. 

You can place only one copy of 
each test instrument into a circuit, 
but after running a simulation, you 
can measure signals at various points 
as long as you don't change the cir- 
cuit itself. 

Analog module 

The analog module works similarly, 
but there are more components and 
different test instruments. Compo- 
nents include resistor, capacitor, in- 
ductor, transformer, NPN and PNP 
transistors (but no FET's or MOS de- 
vices), diode, Zener diode, op-amp, 
battery. AC and DC sources. Test 
instruments include a function gener- 
ator. DVM. dual-channel scope, and 
Bode plotter. 

There are volt meters and am- 
meters in the parts bin; multiple cop- 
ies of each may be inserted into a 
circuit. The function generator pro- 
vides sine, square, and triangular 
waves; the frequency can range from 
1 Hz to 999 MHz; you can also adjust 
the duty cycle, symmetry, amplitude, 
and DC offset. The DVM measures 
current, voltage, resistance, and dB. 
By default, meter characteristics are 
ideal (infinite impedance for voltage 
measurement, zero for current), but 
you can vary characteristics to simu- 
late real-world conditions, and that's 
a nice touch. Similarly, you can alter 
the operating parameters of the ac- 
tive components, and load and save 
different models of the same compo- 
nent. 

Conclusion 

EWB is a wonderful program. It is 
limited in that you can't model very 
large circuits, nor (in the digital mod- 
ule) can you account for propagation 
delays, so you would never be able to 
model a high-speed 32-bit wide 486 
bus. 

But that's not what EWB is intend- 
ed for. It's really intended for first-year 
college or university students coming 
to grips with the fundamentals, and in 
that sense, works admirably. At 
$650. EWB is much too expensive 
for individual purchase. I have dis- 
cussed that with Interactive Images, 



and they are working on a lower-cost 
version. 

I'd strongly urge you to write to the 
company as well. IF the company 
sees a great deal of interest in the 
product, they would be more inclined 
to believe that they can make up 
through volume what they lose in the 
per-piece price. 

Books from Abacus Press 

I have just had the pleasure of per- 
using a couple of thick, dense books 
written by Michael Tischer and pub- 
lished by Abacus press: PC System 
Programming and Turbo Pascal Inter- 
nals. Tischer's stated goal in PC Sys- 
tem Programming is to provide a 
complete system overview, including 
detailed information on hardware, 
BIOS, and DOS. 

Although that is an ambitious goal. 
Tischer for the most part manages to 
achieve it. The book consists of more 
than 900 pages of lucidly presented 
information with lots of example pro- 
grams in assembler, C, Basic, and 
Pascal. All programs listed in the 
book (about 1 MB total) are included 
on a pair of floppy disks, which elimi- 
nates tedious and error-prone typing. 

For example, the book contains an 
excellent discussion of device drivers 
(with examples), a set of routines for 
determining video-card type, using 
extended and expanded memory, de- 
termining CPU type, hard-disk parti- 
tioning, and a whole lot more. All in all, 
these books put to shame certain 
well-known volumes by certain well- 
known industry personalities. The 
Pascal book provides equal meat. For 
example, Tischer shows dis- 
assembled versions of standard Tur- 
bo functions and procedures, il- 
lustrating why DEC and INC are more 
efficient than PRED and SUCC, as 
well as X : = X + 1 . 

Major topics include a complete 
window manager, a swap unit that al- 
lows your Turbo program to shell to 
DOS with a maximum amount of 
memory by leaving only a 1K stub 
behind, and another unit that allows 
you to build a multi-tasking system 
under Turbo. Turbo Pascal Internals 
has about 750 pages, and also 
comes with about 1 MB of source 
code. Neither book is for the begin- 
ner. However, iF you've already mas- 
tered the basics of PC hardware and 
software, these books can provide a 
one-stop source for moving up to 
Guru status. R-E 



MEMORY 
QUIZ 

Find out how much 

you know about 

random access memory. 



ALV N E. SYDNDR 



1 — Most popular RAM devices are 
available in two types, which are: 

(a) metal-oxide semiconductor 
CMOS) 

Cb) 64K bytes 

(c) bipolar 

Cd) high-power 
2 — In dynamic memories, each stor- 
age cell is composed of: 

Ca) PNP ICs 

Cb) a single MOS 

(c) a MOS-processed capacitor 

Cd) silicon chips 
3 — The term "performance" relates 
to how fast the RAM can operate in a 
given environment. That parameter is 
usually rated in terms of: 

(a) bits per second 

(b) transfer time 

Cc) time-temperature 

Cd) access time 
4 — Bipolar memories offer very high 
performance but have the disadvan- 
tage of: 

Ca) being very bulky 

Cb) operating at high voltage levels 

Cc) high power dissipation 

Cd) limited storage 
5 — The great advantage of dynamic 
RAM's (DRAM) lies in: 

Ca) long-term memory storage ca- 
pabilities 

Cb) the small size of their storage 
cells 

Cc) low- voltage operation 

Cd) a long "refresh" time 
6— The term "RAM organization" re- 
fers to the: 

Ca) physical size of the chip 

Cb) method of manufacturing 

(c) grouping of the cells 

Cd) width of the memory word 



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CHRISTMAS CARD 



continued from page 47 



the microphone causes a voltage 
to appear. Do not increase the 
setting until R17 through R20 
are adjusted so as to give a com- 
plete range through each bar- 
graph. The best bet for making 
these adjustments is to play a 
stereo audio source (actually, any 
source will do) at a normal listen- 
ing level. Simply adjust the po- 
tentiometers for what you con- 
sider to be a pieasing or most 
Christmas-like interpretation of 
the sound. 

If you have any problems with 
the device, the first thing to do is 
decrease the setting (counter- 
clockwise) of all the potentiome- 
ters. A filter that still oscillates 
after decreasing the potentiome- 
ters most likely has an incorrect 
component or one that does not 
meet its tolerance. 

For high-Q versions of the cir- 
cuit, sometimes the component 
tolerance is such that the filter 
will begin to oscillate when pre- 
sented with a large input. If that's 
the case, all you must do is inter- 
change the two filter capacitors; 
this old technician's trick usually 
works, assuming that there 
aren't any problems with the 
other components. 

If you still have problems, 
check that the analog ground is 
stable. A variation on that line 
will cause serious problems with 
the operation of the unit. If you 
cannot find the problem, the best 
thing to do is to shut off the dis- 
play by lifting one lead of both Rl 
and D5. With the load of the dis- 
play removed, it's easier to locate 
problems. 

The finished, working board 
can be installed in any kind of 
housing you like, although the 
custom black metal frame adds a 
nice touch, as does the mat that 
keeps the circuitry from view. 
After installing the unit in the 
frame you may want to readjust 
the potentiometers, since the 
frame and front glass seem to 
couple the microphone to the 
surrounding air. Vibrations 
picked up by the device will also 
produce a display; a fan operat- 
ing nearby is almost always dis- 
played. Have fun, and don't 
forget to have a merry Christmas, 
as well! R-E 



DRAWINC BOARD 



continued from page 79 



lower four bits of the data port associ- 
ated with the parallel port you're 
using (LPT1 in this example). 

Since the four most significant bits 
at the data port aren't being used Cat 
the moment), it doesn't matter what 
value we give them. I'm mentioning 
this only because the OUT instruc- 
tion will send a full byte out to the 
port. An instruction such as OUT 
956.1 will send the same four least- 
significant bits to the port as an OUT 
956,177. Those two numbers may 
look very different but the similarity 
between the two shows up when you 
think of the numbers in hex instead of 
decimal. 

Since you want the lower half of the 
byte to be a 1h, any number can be 
stuffed in the upper half of the byte. A 
177 decimal is B1h, so it will be the 
same (as far as our circuit is con- 
cerned) as a 01 h, 21 h, 31h,andsoon. 

The output of the 5088 can be fed 
into the line input of a standard ampli- 
fier or, ifyou'reaDTMFfreak.youcan 
probably connect it to a set of high- 
impedance headphones. There's no 
guarantee of the initial state of the 
lower four bits so there's no telling 
what tone you're going to hear when 
you first connect the circuit to the 
port. 

If you've wired up everything prop- 
erly, you'll hear the tones change as 
you send different data out the port 
but, as you may have noticed, all the 
possible values you can put on the 
lower four bits are legal input codes 
for the 5088. That means there's 
nothing you can send to the port to 
shut the circuit off. While that won't 
cause any electronic problems, it can 
still cause a bit of brain damage. 
There's an easy way around that how- 
ever, since the tone enable input Cpin 
2) is specifically designed to take 
care of the problem. 

You can tie that pin to one of the 
other data lines — bit 7 is a good 
choice — and use that data line to turn 
the chip on and off, A high on the data 
line will enable tone generation and a 
low will disable it, no matter what data 
is being sent on the lower four bits. 

When we get together next time 
we'll finish this thing off by adding 
some circuitry to control the phone 
line, a telephone, and a few other 
things. See you then. R-E 



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SAAVl J199.C0 

TOCOM 1319.00 

EAGLE „ $119.00 

COPY GUARD $59.95 

STARGATE 2000.,, S8S.00 



SB-3 $99.00 

TR1MODE $109.00 

HAMLIN $99.00 

SCIENTIFIC- 
ATLANTA $119.00 

OAK M35B.„ $99.00 

ZENITH..... $175.00 

M. It. Electronics will match or beat any 
advertised wholesale or retail price. 



Your best buys and warranties for 
cable converters and descramblers 
start with a FREE catalog from MD 



For Information Call 

402-554-0417 

To older or request a free catalog 

1-800-624-1150 



EXCELLERATOR 

CABLE CONVERTERS 
WHEN QUALITY COUNTS 




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New Dyna track™ fine tuning provides unmatched picture qua lily 

550 Mhz tuner provides S3 channel capacity 

Sleep timer for automatic shut off within 1 5-90 minutes 

2/3 switchable ICRC / IRC /Standard Switehable 

2 Year warranty, Last channel recall. Favorite channel select. Scan 

Double vented high efficiency transformer Tor cool performance 

Stargate-2001 $99.00 

Stargate-550XL $119.00 With Volume Control 

Don't settle for anything less. 



M£i£EUEER»»Br' LTIHBB c.o.d 



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Quantity Prices 



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$48. $43 



Each 



50 



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King Wholesale 

1-800-729-0036 

Fax number 6173400053 

"No one beats the King's prices!" 



DESCRAMBLERS 



Try the 



Electronics 

bulletin board 
system 

(RE-BBS) 
516-293-2283 



The mote you use It the 
more useful it becomes. 

We support 300 and 1200 
baud operation. 

Parameters: SN1 (S data 
bits, no parity, 1 stop bit) 
or 7E1 (7 data bits, even 
parity. 1 slop bit). 

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tiles to increase your 
access. 

Communicate with other 
R-E readers. 

Leave your comments on 
R-E with the SYS0P. 



RE-BBS 
516-293-2283 



PROTO QUICK 28, single board computer with pro- 
totype area, $69.00, SOFTWARE SCIENCE, 3750 
Roundbollom Road, Cincinnati, OH 45244. (513) 
561-2060. 



FLUKE 



Model 
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75. 
77. 



s 68 
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s 135 



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▲ NEWl Model 45 . . . '535 ▼ 

■ ■ £ KEL VI N Electronics 

■ u "7 Fa-rciiild Ays . flainview. NY ttaoj 
^■■(516) 349-7620 1(800)645-9212 




RADIO tubes, parts. Extensive listings. $1. 00 (re- 
fundable). DIERS, 4276- E6 North 50th Street, Mil- 
waukee. Wl 53216-1313. 

BOOKS on Tesla coils, lasers, robotics, elec- 
tronics, computers & more! Write: Free catalog. 
Box 596-R, Logan, Utah 84321. 1 (800) 359-0466. 

FREE catalog: Save hundreds on sought alter elec- 
tronic, electro mechanical, and computer related 
hardware and components — including hard-to-find 
items. Call toll free: 1 (800) 776-3700. AMERICAN 
DESIGN COMPONENTS/ Depl. 119-120, B15 Fair- 
view Avenue, Fairvrew, NJ 07022. 



CABLE TV 
"BOXES" 

Converters — Descramblers 
Remote Controls— Accessories 

* Guaranteed Best Prices * 

* 1 year Warranty — C.O.D ,'s * 

* Immediate Shipping * 

* FREE CATALOG * 

Call or Write 

TRANS-WORLD CABLE CO. 

12062 Soul riwest 117th Court, Suite 126 

Miami, Florida 33186 

1-800-342-9333 



VCR technicians. Tech lip to remove any Fisher 
idler wheel quick. $5.00. BERGE SYSTEMS, PO 
Box 95, Buitalo, NY 14205. 

PREVENT burglaries! Practical home security 
quide. Topics from burglar techniques to alarm in- 
stallation. Free details! MIDNIGHT RESEARCH, 
4129 NW 88th Avenue, Suite 282, Sunrise, FL 
33351 . 

CABLE TV brokers and distributors high volume of 
descramblers Jerrold SB-3 refurbished or as is. con- 
verters Jerrold models DRX-400. JRX and hand 
remote control [no Canada sales for descramblers). 
Affitech. ask DANIEL PERREAULT (514) 
656-9510. 

KITS, MC68701 programmer $135.00, morse code 
keyboard $75.00, ten meter FM conversion $25.00. 
SINGLE CHIP SOLUTIONS, Box 680, New 
Hartford, CT 06057-0680. 



CABLE DESCRAMBLERS 
OAK M3SB COMBO S39.95 



Jerrold, Zenith, Hamlin, Sci. Atlanta, Pioneer 
& MORE! OUR PRICES ARE BELOW WHOLESALE! 

CABLE-*- PLUS 

14417 Chase St. #4B1-A Panorama City. CA 91402 

1-800-822-9955 • Other Info. 1-818-785-4500 

NO CALIF. SALES - DEALERS WANTED 



DESCRAMBLER specials, RTC-56 combo 
$150.00, M-35-B combo $39.00, Tocom 5503A 
combo S200.00. 5501 descrambler $115.00, Jer- 
rold 400 combo $125.00, Hamlin CRX-6600 com- 
bo $125.00, Zenith Z-Tac $225,00. Tri-Bi super 
fast $79.00, SA-3-B $79.00. Information (702) 
647-3799, orders only 1 (800) 622-3799 S.A.C.. 



92 




DESCRAMBLERS 



***** STARRING ***** 

JERROLD, HAMUN, OAK 

AND OtHES FAMOUS WANUFACTUWEBS 

• RNf ST WWfiAVTT FWOCIWM «UN1A»LE 

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FOW FKIt CATALOG ONLT 1-S00-345-S9 2 7 
ton ALL INTOmWATtOW 1->H-709-993T/ 



SATELLITE TV 



- — - PACIFIC CABLE CO., INC _- — , 
t ■ J 732SMi Reseda Blvd., Oept.1000 pa^ 
-■— -■ Reseda, CA 91335 



SCANNER buffs, national and international fre- 
quency listings with allocations. Send $11.00 U.S. 
for booklet to: BOX 1051, Station C, Kitchener, On- 
tario, N2G 4G1 Canada. 

ARTWORK created for use in printed circuit board 
production from your engineering schematics. Pro- 
fessional quality hardcopy, gerberfile, or photoplot- 
ter outputs, Reaonable rates. Send tor details to: 
JTD ENGINEERING, 10623 Grandview Place, Alta 
Loma.CA 91701. 

SURPLUS educational equipment, shortwave re- 
ceivers adjustable 50 to 70 MGHZ, 6 meter, with 
private line. Information! ELECTRO TECH 
SCHOOLS, 120-N. Mechanic Avenue, Alliance, OH 
44601. 



INVENTORS 



INVENTORS! Can you patent and profit from your 
idea? Call AMERICAN INVENTORS CORPORA- 
TION for free information. Over a decade of service 
1 (800) 338-5656. In Massachusetts or Canada call 

(413) 568-3753. 



VIDEOCIPHER II manuals. Volume 1 - Hardware, 
Volume 2 - Software - either $34.95. Volume 3 - 
Projects/Software, Volume 5 - Documentation or 
Volume 6 - Experimentation 544.95 each. Volume 
4 - Repair 599,95. Cable Hacker's Bible -$34.95. 
Clone Hacker's Bible - $34.95. Catalog - 53.00. 
COD'S (602) 782-2316. TELECODE, PO Box 6426- 
RE, Yuma, A2 85366-6426. 

FREE catalog — Lowest prices worldwide, save 40 
— 60%. Systems, upgrades, parts, all major brands 
factory fresh and warranted. SKY VISION, 2009 
Collegeway, Fergus Falls, MN 56537, 1 (800) 
334-6455. 

CABLE TV secrets — the outlaw publication the 
cable companies Iried to ban. HBO, Movie Channel, 
Showtime, d esc ram biers, converters, etc. Sup- 
pliers list included. $9.95. CABLE FACTS, Box 711- 
R, Pataskala, OH 43062. 



INCREDIBLE NtONITOH BUY! 
THEY WON'T LAST LONG AT THESE PRICES! 

9"„TTL (Open Frame) Monitors 




Cable TV 
Descramblers 

If you And a better deal, 
we'll better our deal. 
'Jerrold 'Tocom 'Hamlin 'Oak 

'Scientific Atlanta 'Zenith 

Ask about our extended warranty 

program. 

COD. Visa, M/C welcome. 

Free Call - Free Catalog, 

videoTech 800-562-6884 

3702 S. Virginia St., Ste. 160-304 
Reno, NV 89502. 





Also Available 

12", (Open Frame} TTL 12V, 

Green Screen #6811 s 19.99 

FREE CATALOG 

Included with your order: Call 
1-B0Q-776-3700 or send order lo: 

AMERICAN design ccwoerrs 

Deft JH 120 815 Fdffwew *.<enue PO Bo 220 
Farview. Nj 07022 Free catalogue without purchase 
Simply write ADC or cor catalogue department 20].£mi 



VIDEOCYPHER II descrambling manual. Sche- 
matics, video and audio. Explains DES. EPROM, 
CloneMaster, 3Musketeer, Pay-per-view (HBO. Cin- 
emax, Showtime, adult, etc.) $16.95, $2.00 postage. 
Collection of software to copy and alter EPROM 
codes. $25.00. CABLETRONICS, Box 30502R, 
Bethesda. MD 20824. 



BUSINESS OPPORTUNITIES 

EASY work! Excellent pay! Assemble products at 
home. Call for information. (504) 641-8003 Ext. 
5192. 

MAKE $50/hr working evenings or weekends in 
your own electronics business. Send for free facts. 
INDUSTRY, Box 531. Bronx, NY 10461-0208. 

YOUR own radio station! AM, FM, TV, cable. Li- 
censed unlicensed. BROADCASTING, Box 130- 
F12, Paradise. CA 95967. 

INVENTORS: We submit ideas to industry. Find out 
what we can do for you 1 (800) 288-IDEA. 



fLMARK V ELECTRONICS, INC. 

all Competitive Pricing * Fast Shipping since ibss 



ORDER IN CALIFORNIA 800-521 -MARK Wj 

ORDER OUTSIDE CA 800-423-3483 \*£ 

FREE CATALOG & INFORMATION (2(3)088-8988 B3R 
FAX (213) 088-6868 Vi' J' 




A indicates ihe level of difficulty in the assembling of our Products. 

AMPLIFIERS KJT ASSMB, 

MODEL DESCRIPTION 

TA-28MK2 Digital Voice Memo ii S 30.00 

TA-50A* Multi-purpose MalDdy Generator A 1284 $"20 

TA-50C Multi-Purpose Melody Generator A. 13.65 18.71 

TA-120MK2 35W Class "A" Main Power Mono Amp A A 28 50 39.80 

TA-300 SOW Multi-Purpose Single Channel Amp A 20.00 29.00 

TA-302 60W StareD Power Booster (w/casef AA 70.00 

TA-323A 30W*2 Stereo Pre-main Amp A 29.50 30.35 

TA-377A Hi-Quality FET Stereo Pre-Amp AAA 59.95 75.00 

TA-400 40W Solid Stale Mono Amp A 28,00 34.93 

TA-477 120W Moslel Power Mono Amp AA 68.00 85.00 

TA-8O0 SOW-iSOW DC Pre-Main & Powei Amp AA 60.92 79.20 

TA-B02 80W*80W DC Slereo Main Power Amp AA 45.94 59.72 

TA-820A 60W . 60W OCL DC Pre- Main Stereo Amp A A 40.39 49.37 

TA.1000A TOOW Dynamic Class "A'Main Power Mono Amp AA. .. . 59.69 S0.58 

TA-1500 100W*2 Class 'A- DC Slereo Pre Mam Amp AAA 73.70 95 81 

TA-2200 FET Super class "A" DC Pre-Amp AAA 47.70 58.24 

TA-2400A Electronic Echo & Reverberation Amp AAA* 96.00 

TA-250D HO Pre-Amp. w/1 band graphic equalizer * 68.80 

TA-28O0 HI-FET IC Pre-Amp. w/3 way tone control AA 48,90 63.57 

TA-30O0 Stereo Simulator (mono TV , r any mono source) AA 27.00 3a. 50 

TA-3600 300W HQ Hi-Fi Power Mono Amp AAA 79.00 103.00 

POWER SUPPLIES KIT ASSMB. 

TFMOCA 0-1 5V 2 A Regulated DC Power Supply iw-'casei AAA . S J 69.50 

TH-355A 0-15V 5A Regulated DC Power Supply A 14.55 20.76 

TR-355B O-30V3A Regulated DC Power Supply A 14.55 20.76 

TR-503 0-50V 3A Regulated DC Power Supply AA 15.75 22.65 

WSTftilMiiSifs _ Kit asSmb. 

5M-43 3 V? Multi- Functional Led D.P M iw.-'ABS plastic easej AA S 34.50 S 43-00 

SM-48 4'A Hi-Precision O.P.M.AAA 38.00 48.00 

SM-48A 4W HiPrescisionDP.M (WJABS plasllC case) AAA 41.20 52.00 

SM-49 3Vi Multi- Functional LCD C.P.M. (w/hold (unction) AA 36.00 44,50 

SM-100 150 MC Dig ilal Frequency Counter AAA 79-00 90.00 

FC-1000A 1 GHz Frequency Counter * 179.00 



Beginner 



Advanced * Assembled 



SM-49 




' Free gilt for any purchase during Christmas Season 
MISCKU.ANEOI.-S 



tax ass-be: 



MODEL DESCRIPTION 

TY-23B 3 Channel Color Light Controller AAA*. .. S 51 20 

TY-25 Stereo Loudspeaker Prosector A t3,85 

TY-35 FM Wireless Microphone 1022 

TY-36 AC'DC Quartz Digital Clock A 1900 

TY-38 Sound/Touch Conlrol Switch A 12.00 

TY-41MKV Irtfared Remote Control Unil w.'case AAA 20,00 

TY-42 Bar/Dot Level Meier AA 24.15 

TY-43 3 1 * Digital Panel Meter A „.. 29.00 

TY-45 20 Sleps Bar/Dot Audio Level Display A A 3845 

TY-47 Superior Electronic Roulene AA 19,46 

SM-222 7 Band HI-FI Graphic Equaiiier AAA 26.80 

SM-328 4 Channel Protessiqnat Color Light Controller* 

SM-333 Audro'Video Surround Sound Processor AAA* 62.00 

SM666 Dynamic Wo.se Reduction A 26.00 



S 65.00 
19.85 

26.20 
35.00 

38.00 

46.14 
27.24 

38.80 
139.00 
70.00 
34 00 



T1KTAI. CABINKTS WITH AI.PvitNUM PANEL" 

MODEL H" « W i D" MAT CHI KG PRICE 

LG-1273 3" t2 _ T TA-2800.TA-377A, TA-2200 5 22.16 

LG-1684 4" 16" 8" TA-323A TA377A. TA-2200 26.64 

LG-1924 4" 19" lite" TA-802. TA-820A . TA -1500, TA-120MK 2. TA-800. TA-UXWA 32.00 

LG-1925 5" 19" 11*4* TA-477 , TA-800. TA- 1 500. TA-1 000*. TA-3600 35 00 

LG-19B3 2V 19" 8" TA-377A. TA-280O. TA-2200 TA-120MK 2 28,50 



MODEL 
9001 

«OD2 
t003 

#004 
#005 
#006 
S007 



POWER TRANSFORMERS 



DESCRIPTION MATCHING PRICE 

28V i! 6Ato30Vi2 6A TA- 800. TA-802. TA.820A. TA-1 0O0A. TA-1500 S 26.00 

36» »"3A TR-503. TA-323A, TA-400, TA-300 21 00 

40V j 2 6A TA-477 27.00 

24V i 2 6A TA-120MK2 _ 21.00 

26V < 2 3A TR-355B 15 00 

18V x 2 5A TR-355A 14.50 

52V i 2 aA TA-3600 42.00 

I- IUJ -I -. 1 V I L ' -l- ' Iliait B -l l f-iL l iit-l^-l^-i-liiiiy i UlL^I^I irTiTuia 



Mon thru Fri 9:30 i 



Sal 10:00 am lo 5 00 pm 

MARK V ELECTRONICS, INC. -8019 E. Slauson Ave, Montebello, CA 90640-^SH 



CIRCLE 93 ON FREE INFORMATION CARD 



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THE ELECTRONIC GOLDMINE 




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unique, barfain 

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MINI GEIGER COUNTER 



Defects ALL Types ol Radiafon 
Uses Sensitive Alpha Window Tuts 
Cpeates from W Batey (red bxl.} 
Cone with PC Bead. Pins. 
Tube and Inanxfons 
Sim of PC Boarct rit9" 



C6430 $59.95 




4KV TRIGGER COEL 

Ua win any ante * 
'ait -;: needs a 
3 bad *KV trigger, 

M7O0 S1.2S EA. 
100 fex $90.00 



INVERTER 
TRANSFORMER g3 

Small 4 Lsad d^sMrmer 
for use wlh 555 C to coiwt 
1ZVDC to 2SIY tor ejtjIjV 
lI'jOfBSl tlfcS w.lh SOWTliic. 
N17Q3 $2JX> EA 
1,000 tor St t 500 



CDS CELL 
ASSOI 

Great 




projects 
Experiments 

Tnta 

liielr njsi__. 
ligfi 5 d^ereni fy&s. \\ 
G764 
5 for $2,00 



GIANT HORSESHOE 
XENON STROBE TUBI 

Livges tarMctae Tube *e I'M 
ever seen! Make a behEnauih 
slrabe En IrqHen wvfim W H*- 
lowttft. or um li in a nt-opfw rt a 
dism slrcbti 51a: z* nil x Mfl" 
witfe, glass tubing dia. S/16". 
Dpaa^s on 300VOC and can be 
used with our 4K<t ir-ao*-" t.Trrj- 
kuw (stoctf in too to itnj 

G762 $7.00 EACH 




RARE EARTH MAGNET, 
Many times suonos man aw 
magnerj. iiee are *roung Bt 

iflrttfsslianoisicDiri'nercafiyMit- 
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Great 1st ineuianuS; o' >toervieri|£ anrj ^piica- 
li&TS- Mcrrriiy thes sell lor lw $50 eatl tui 
iress are jyrpta and f*ft a ft* Chip^dos rot 
e«K£ peddnnarct). G7G5 $9,00 



MINIMUM ORDER: SI 000 pkjs $3.00 sftcjwig artf harcjling 



SEND OHDERS TO: The Electronic GoUmn 
P O Bo< 5J03 Scofedafe. AZ S5241 
PHONE OROEHS: (60a 451-7154 



CIRCLE 177 ON FREE INFORMATION CARD 



CONSOLIDATED 




VOLUME 1 - TEST EQUIPMENT 



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"Volume l-Test Equipment" 

112 pages packed with specifications on Ihe most 
popular (6sl equipment like B&K, Beckman, ARL 
Simpson. Mercer, Soar, Goldstar and Vector-Viz. 
Choose from; hundreds or multimeters, oscilloscopes, 
frequency counters. Junction generators, power supplies 
5 more. Send 55.00 check or money order, or call 
1-600-543-3563 today & use your Mastercard or Visa. 
Consolidated Electronics, Incorporated 
705 Watervllet Avenue., Dayton, Ohio 45420-2599 



IKE NELSON'S 
OV1E VIEW SALES 



CABLE T.V. CONVERTERS 

OESCRAMBLERS REMOTES 

(No Illinois Sales) 

□ JERROLD DOAK 

□ SCIENTIFIC ^-HAMLIN 

ATLANTA D6MOS. 

□ LOW PRICES WARRANTY 



MIKE HAS 10 YRS. EXPERIENCE 

IN THE CABLE BUSINESS. 
CALL 708-766-5222 
0R MOVIE VIEW SALES 

WRITE p '°- BOX 26 

WOOD DALE, IL 60191 



LET the government finance your small business. 
Granls'loans lo $500,000. Free recorded message: 
(707)449-8600. (KS1). 

CIRCUIT board design services: development 

schematic and PC6 layouts. Quick turnaround, 
(503) 345-4609, SKYCHASER, 980 Sherwood 
Place, Eugene, OR 97401, 

MAKE $75,000 to $250,000 yearly or more fixing 
IBM color monitors (and most brands). No invest- 
ment. Start doing it from your home. (A telephone 
required.) Information, USA, Canada $1.00 cash. 
US funds, other countries $8.00 RANDALL DIS- 
PLAY, Box 2168-R, Van Nuys, CA 91404 USA. 

VIDEO magic. Start your own business. Video 
security system. No wiring required. Ideal for 
small businesses, homes, property, marina. 
S950.00 gets you started. Camera only $490.00. 
Call: VIDEO MAGIC (516) 249-4216. 



K.D. VIDEO 

FOR ALL YOUR CABLE TV NEEDS 
WE SPECIALIZE IN DEALER PRICING 



QTY 

Jerrold (Type) SB-3 
Jerrold (Type) Tri-Bi 
Scientific Atlanta SA-3 
Hamlin MLD-1200 
OakN-12Vari-Sync 
Jerrold 550 Converter 
Jerrold 400 DRX-3DIC 
(With Built in SB-3) 



1 10 20 

89,00 56.00 43.00 
119.00 69.00 65.00 
129.00 80.00 75.00 
99 .00 59.00 45.00 
99.00 59.00 58.00 
99.00 75.00 68.00 

69.00 109.00 100.00 



1-800-327-3407 

Call us tor prices on large quantities 
K.D, Video PO Box 29538. Mpls , MN 55429 



PLANS AND KITS 

MINIATURE FM transmitters! Tracking transmitters! 
Voice disguisers! Bug detectors! Phone Devices! 
More! Available in kits or assembled! Catalog $2.00: 
XANDI ELECTRONICS, Box 25647, Dept. 60L 
Tempe. AZ 65285-5647. 

CATALOG: hobby/broadcasting/HAM/CB: Cable 

TV, transmitters, amplifiers, surveillance devices, 
computers, more! PAN AXIS, Box 130-F12, Para- 
dise. CA 95967. 



REMOTE CONTROL KEYCHAIN 

Complete w'mini-trnnsniiiter 
.. : »nd+5 vde RF receiver..;! 
Fully ns&*mWed including plans 
to build your.own aulo alarm . 
Quantity discounts a vail able I 

Check. Visa or M.C 

as 

VIS1TECT INC. BOX S442, SO.SAN FRAN./CA. 9TOBO ' 

(415) 872-0128 : ; Fax (415) 872-2635 




tf**iyl rtc Check,Viaa or M.C 
<J>Z4.!JO Add S 3 ehippin 



INVESTIGATORS, experimenters — Quality new 
plans. Micro and restricted devices. Free catalog. 
Self addressed stamped envelope required K EL- 
LEY SECURITY INC., Suite 90, 2531 Sawtelle 
Blvd.. Los Angeles, CA 90064. 



SURVEILLANCE transmitter kits! Four models of 
each; telephone, room, combination telephone/ 
room transmitters tune from 65 to 305 MHz. Catalog 
with Popular Communications and Popular 
Electronics book reviews of "Electronic Eaves- 
dropping Equipment Design," $1.00. 
SHEFFIELD ELECTRONICS, 7223 Stony Island 
Ave., Chicago, IL 60649-2806. 

CB Tricks II book. Power amplifier design and theo- 
ry, UHF CB tune ups. Send $19.95 MEDICINE MAN 
CB, PO Box 37, Clarksville, AR 72830. 

KITS — alarms, games, and test equipment. Send 
$1 .00 for catalog. R AKJ AB, PO Box 1 875, Apopka. 
FL 32704. 



New Laser 
Diodes MS 



LASERS 

Helium-Neon 
Laser Tubes 



from s 25 



p 

i New Visible** 
Diode Modules 



FREE CATALOQ COMPLETE HELIUM-NEON 
CALLORWfttTETOOAYl | LASERS FROM '110°° 
MEREDITH INSTRUMENTS ?c He* lW.'G pni-a* AZ&S3l',':&>^3*.«B? 



PC/TV Interface — RGB to TV/video/ VCR. Switch- 
able between PC and composite video inputs. 
Channels 3 or 4, RF output. Complete PC card kits 
$59.95. PC board only $19.95 Mass. residents add 
5% sales tax. INOVONICS CORP. 9 Barllett St., 
Dept. 36, Andover, MA 01310. 

DESCRAMBLING, new secret manual. Build your 
own descram biers for cable and subscription TV. 
Instructions, schematics for SSAVl, Gated Sync, 
Sinewave, (HBO, Cinemax, Showtime, UHF, adult) 
$12.95. $2.00 postage. CABLETRONICS, Box 
30502R, Bethesda, MD 20824. 

LASER lighting entertainment systems. Create 
your own 3-dimensional laser light shows with these 
professional secrets! Detailed mechanical and elec- 
trical schematics, designs for any budget! $20.00. 
MILLENNIUM, 229 McAfee, Thousand Oaks, CA 
91360. 



COMPUTER KITS 



General Technics 

Qua Illy Computer Systems 

Post Office Box 2676 

Lake Ronkonkoma, NY 11779 

(616) 9S1 -9473 



General Technics Computer Kits 

include a complete line ot &flfcS, 2S6, 

and 386 niMiek. 'phey are designed /^— 
10 offer ihc highest degree of quality £ 




55^ 



and reliability available loday. They're also fun, easy lo build, 
educational, fully IBM compatible, very powrful, and at 
wholesale prices. All kitsarenre-Ttsiedand Include a free step 
by step assembly manual, software, one year warraruv and our 
24 hour supporVorder phone line. Assembly is available. 



ask for your free catalog 



CAR alarm schematic with instructions, easy con- 
struction and installation. $6.00: HUNTER, 1802 
Cook, Duncan, OK 73536. 

DAZER II personal protection device! Plans $8.00. 
Lasers! Transmitters! Detectors! More! Kits or as- 
sembled! Catalog $2 00. QUANTUM RESEARCH, 

16645-113 Avenue, Edmonton, Alberta T5M 2X2. 

PEN transmitter: Sensitive micro FM transmitter, 
housed inside standard size pen. Latest surface 
mount technology. Complete kit and instruction 
S42.95 MIERONIC-INT., Box 5726. Sherman 
Oaks, CA 91413. 

BUILD this Pseudo car alarm-Led flasher with auto- 
matic disable via the ignition switch. Detailed sche- 
matic with educational information $2.50. LMT 
ELECTRONICS, Box 4268. Diamond Bar, CA 
91765. 

UNIQUE projects. Build an infrared motion detector, 
ultrasonic distance meter, digital rain gauge. Com- 
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PCB and schematic CAD software. Easy multilayer 
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10565 Bluebird Street, Coon Rapids, MN 55433. 



Pay TV and Satellite est rambling 
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REMOTE control. 20 page package gives info and 
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CONTINUOUS CONCEPTS, PO Box 60414, San 
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PLANS! Vehicle alarm battery backup system. 
Schematic, artwork, instructions, $10.95. AGK 
ELECTRONICS, N.K. PO Box 28123. Winnipeg, 
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POWERFUL single-chip FM room transmitter, size 
of a postage stamp, transmits to any FM radio up to 
one mite away. Complete kit $19.95 postpaid. 
HERTZ MICRODEVICES, Box 41771, LA. CA 
90041. 



EDUCATION & INSTRUCTION 

MAGIC! Four illustrated lessons plus inside infor- 
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F.C.C. Commercial General Radiotelephone li- 
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LEARN IBM PC assembly language. 80 pro- 
grams. Disk S5.00. Book $18.00. ZIPFAST, Box 
12238, Lexington, KY 40581-2238. 

CONSUMER advocate. Help sources, any problem. 
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FL 34635. 



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CABLE BOX REPAIR 

JERROLD 400 opportunity CATV repair manual. 
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2-1/2" SANYO TWEETER 



Paper cone wilh gold tone 
dust cap. 8 oz. magnet. 
8 ohm. 1/2-ferro fluid 
voice coil. Power 
handling: 50W RMS, 
70W max. Frequency re- 
sponse: 3K-20KHZ 



#RP-271-020 $1 M $1"95C 



f>. 



SUPER HORN TWEETER 



Original pieso tweeter 
made by Motorola. 
SPL=94dB2.83V/1M. 
Response: 4KHz- 
27KHz. Handles ap- 
proximately 50 watts. 

#RP-270-010 



«*P 



$5 M $4 M $3 9: 

[1.9) 110-79* UO-vi 



2" DOME MIDRANGE 



Textile dome 

mid range made by 
Philips. S ohm. 
SPU90dB 1VW1M. 
30 W RMS, 40 W 
max. Response: 
550-5KHz, 

#RP-280-210 



■ 






$27 M 

M-3& 



$25™ 



15" SUBWOOFER 

i 




Dual voice coil. 40 oz. magnet- 6 ohm 
imp. 100WRMS, HDWmax. Response: 
20-1 2KHi Resonant frequency: 21 Hz. 
SPL=93dB 1YW1M. 



#RP-290-190 $54 s ° $49 M 

(1-3) f*-up> 



SUBWOOFER XOVER 




200W RMS crossover designed 
specifically for use wilh dual voice coil sub 
woofers. 1 2 dB per octave roll-off at 
ISO Hz. 



#RP-260-220 



$28™ $24" 



340 E. Flrtl SI.. Dayton, Ohio 45402 
Locnk t -51 3-222-0 173 
FAX: 51 3-J2Z- 4S44 



10" POLY WOOFER 

Medium 

duty. 60W 
RMS, 80 W 
max, 14oz. 
magnet 
Response: 
25-2.5KI Iz. 
fs=28Hz. 




#RP-290-096 



$18 M $16" 

<i-3> l*-up1 



TITANIUM COMPOSITE 
TWEETER , 



The advantages of 
boih hard and soft 
dome technologies. 
8 ohm. Ferro fluid 
cooled voice coil. 
SPL=90dB 1W/1M 
50W RMS, 70 W 
max. 4" round. 
Polydax 
#DTW100T125. 



#RP-270-047 




12" CAST FRAME 
WOOFER _ ^ 




12" vifoofer made m the USA by Eminence. 
Paper cone and dust cap with treated cloth 
surround. B0 oz. magnet. 2*1/2" vented 
voice coil. 8 ohm. 170W RMS, 235W max. 
40-4, 5KHz response. 



#RP-29tM47 



SPEAKER BUILDING 



BOOK 

Revised edition 
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rr 



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- t5day money bach guarantee - S15.00 minimum outer- We accept 
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Foreign customers please send S5.00 U.S. lunds for ca<aiog coslage. 



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WANTED 



INVENTORS! Confused? Need help? Call IMPAC 
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FREE CATALOG! 
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may we suggest about 

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:lung association ' 

Thp nrirtsEnnias S?i»l "People 1 * 



COLLIMATOR PEN 

(INFRA-RED) 




LASER DIODE 

(INFRA-RED) 




LASER DIODE 

(VISIBLE-RED) 




LASER DIODE 
(VISIBLE-RED) 



CO 
O 

Z 

O 
rr 

O 



LU 

6 

< 
EC 

96 




POWER SUPPLY 




UNICORN - YOUR LC. SOURCE! 



* Output: 2.5 mW (max.) 






FPHOMS 










• Operating Voltage: 2.2-2.5V 

• Wavelength: 820nm 

• Collimation: .18mrad (typ.) 

• Size: 11mm diameter 

STOCK # PRICE 


STOCK • 


PINS 


DESCRIPTION 






1-24 2599 


loot 


1702 

2708 

2716 

2716-1 

TMS2716 


24 

24 
24 
24 
24 


256 x 4 1 us 
1024 X 8 45ns 
2043 x 8 450ns (25v) 
2048 x 8 350ns (25v) 
2048 X B 450ns 






3.99 ; 

6.49 ( 
3.29 ; 
3.79 ; 
6.29 

3.99 ; 
3.79 : 
3.79 : 
369 
3,19 ; 


.79 

.17 
.13 
60 
.93 
.79 
.60 
60 
.51 
.03 
.50 
.89 
.98 
1.79 
160 


3.41 
555 
2.62 
3.24 
5.38 


SB1052 $39.99 

• Output: 10 mW (max.) 

• Current: 90-150 mA 


27C16 

2732 

2732A-2 

2732A 

2732A-4 


24 
24 
24 
24 
24 


2048 X 6 450ns (25V-CMOS) 
4096 x 8 450ns (25v) 
4096x8 200ns (21V) 
4096x8 250ns (21 v) 
4096 X B 450ns I21v) 






3.41 
3.24 

324 
316 

2.73 


• Operating Voltage: 2.2-2.5V 

• Wavelength: 820nm 

STOCK * PRICE 

SB1053 $9.99 

« Output: 5 mW (max.) 

• Current: 65-100 mA 

• Operating Voltage: 1.75-2.2V 

• Wavelength: 780nm 

STOCK # PRICE 

LS022 $19.99 


TM52S32 24 
TMS2532P 24 
27C32 24 
2764-20 28 
2764 28 
2764A-20 28 
2764A 28 
TMS25S4 28 
27C64 28 
27128-20 28 
27128 28 
271 28A 23 
27C12B 28 
27266-28 28 
27256 28 
27C2S8 28 
27512-20 28 
27S12 28 
27C512 28 
27C1024 32 
68764 24 
68766 24 


4096 X 8 450ns (25v) 

4096 x B 450ns (25v-One Time Programmable) 

4096x8 4S0ns (25U-CMOS) 

8192x3 200ns (21v) 

8192x8 250ns (2I») 


5.79 
1.99 
4.19 
399 
3.79 


4.95 
1,70 
3.58 
3.41 
324 


8192x8 20Ons (125»J 
8192x8 250ns (12 5vl 
8192x8 250ns (25») 
8192 X 8 2S0ns (21V-CMOS) 
16.384 x 8 200ns (21v) 






3.99 3.79 
3.29 3.13 
6.79 6.45 
4 19 3.96 
5.79 5.50 
5.09 4.84 
5.79 5.50 
S.79 5.50 
5.29 5,03 
4.79 4.55 


3.41 
282 
5.81 
3,58 

4.95 


16.384 x 8 250ns (21v) 
16,384 x 8 250ns (21v) 
16.364x8 250ns (2 1v) 
32.728 X 8 200ns (12,5v) 
32.768 x 8 250ns (12.5v) 






4.35 
4.95 

4.95 
4.53 

4.09 


• Output: 4 mW (max.) 
» Current: 20 mA 

• Operating Voltage: 2.2-3. 0V 

• Wavelength: SSSnm 

STOCK * PRICE 

LS3200 $129.99 


32,768x8 250ns (12.5V) 
65.536x8 200ns (12.5V) 
66.538x8 250ns (12.SV) 
65.536x8 250ns (125V-CMC 
131,072x8 200ns (12 5v-CM 
8192x8 450ns 
8192 x 8 450ns 

j&pwic 

W I Lf CTR 

O10 Canoga Ave.. Unit B-8 
UTSIDE CALIFORNIA: 
1 CALIFORNIA: 
RDER BY FAX: 

Minimum Ord 


S) 
OS) 




5 29 5,03 
7 49 712 
6.99 8.64 
699 6.64 
17.99 1709 


463 
641 
5.98 
5.98 
15.38 


N KS 

■ Chatsworth, GA 
(800) 824-3432 
(818) 341-8833 
(818) 998-7975 

et S 15.00 


13.99 1 
1499 1 


5.29 
1.24 

Onl 


11.96 
12.82 


• Input: 115/230v 


Imq Uf rCoi-d 




• Size 7" L x 654" Wx2»H 

• Output: +5 volts @ 3.75 amps 
•Output: +12 volts @ 1.5 amps 

• Output: -12 volts @ .4 amps 

STOCK # PfllCE 

PS1003 $19.99 


E333a 


n 


91311 

(Orders 


ft 



CIRCLE 195 ON FREE INFORMATION CARD 



QUALITY PARTS • DISCOUNT PRICES • FAST SHIPPING 



mtmmamMM 



DIGITAL CLOCK AND 
APPLIANCE TIMER 



— .:: ! :.,,,:■.. ' " — 

ONE MINUTE TIMER 



)jgKal clock and appliance 
Imer removed from automatic 
iloclric coffee makers due 
o design changes. Operates H-* 
>n 1 20 Vac and is capable r> 
if turning on appliances 
(rawing up to 10 amps. 
because of the application I hey were designed 
or they automatically lur n otf after two hours. 
Some have surface blemishes. 4.2" X 2.45" X 
.1" deep. Seige or ivory with brown trim. 
CAT* MCT S6.50 each 




ItWDGiGEARHEAD 
; MOTOR : 



•<XB- 



Soho» GBL 35-DH-21Q8CM0Y 
Powerful little 
Q&artaarJ motor. 
4QRPM@12Vdc. 

0.5 amps ( "o toad). 

32 RPM with load. 

Operates at lower voltages with reduced speed 

and torque. 6.3 pound inches torque. Stall: 27 

pound inches. 3-1" tong X 1.375" diameter. 

Shalt; 0.187" dia. X 0.75" long. 

CAT#MOTG-14 $11,50 each 
10 for J100.00 



15QMICR0AMP! 



150' microamp full scale, 

2.165- X 1.875" X jf\ 

0.96" deep 

Face is 1.965" X1*1". 

White background with 

black and red scale. 

Two types. One is marked "Modulation" and 

has aO - 100 scale. The other has two 

scales, "RF" and 'SWR". Otherwise meler 

are Idem leal. 




"Modulation" meter 
RF/SWR meter 



CATKMET-21 $3.50 
CAT*MET*22 $3.50 




This while box with 
a blue button will 
drive you crazy 

Box measures 3 1/4" 
square X 2" high. When 
the burton Is pressed 4 LEDs light and a beep- 
er pulses. Every 15 seconds one led goes out 
and the speed of the beeping increases. At 
trie end of 60 seconds the unit gives off a long 
beep followed by a low squelch, all LEDs shut 
olf and the unit stops. Unit requires a 9 voir 
transistor battery (not Included) to operate. 

CAT#TMR-t $2.25 each ■ 10 lor $20.00 



WfiyA 



^SWITCHES 



SPLIT PUSHBUTTON 

Miirq .. ,i -ill; 1 fl« 

Rated $ mq» 9 1 25*250 Vac 
Black plastic pushbutton. 
Switch body: .82" X .94" X 65" 
CATtPB-1* S1.65M. "10for $15.00 

PUSHBUTTON SWITCH q 

GC/Tfwm&en* 35-420 (S 

S. P . S.T. normal fy open morrwnta^ pf 
pushbutton switch. Red plastic \~J 

actuator 0.57" diameter. Chrome 
bezel 0.68" diameter. Threaded bushing 
mounts in .50" diameter IidIo. Rated 
3 amp @ £50Vac. Solder loop Terminal*. 
CAT* PB -20 SI. OO each 

THUMBWHEEL SWITCH 

1 pole 10 position 
decimal encoded 
switches which 
interlock to make 
up desired number 
or digits. Terminates to 11 pc pins [1 com- 
mon and 10 poles). Each section measures 
.31' wide X .20" high X 78" deep. End plates 
can be added to form a .94' high bezel. 

CAT#SWTH-» St. 25 each 
10 lot S10 00 

2 END PLATES - CATeSW-BEC 31 DO/Set 

MINIATURE TOGGLE SWITCH 
Rated: 9 amps @ 120 Vac 
S.P.S.T. (ON-ON) solder lues 
CATaMTS-4 S1.35eacti 




S.P.S.T. (ON-ON) PC. mount 
CAT* HTS-4PC SI. 00 eech 



i 



WALL TRANSFORMERS 




ALL PLUG DIRECTLY 

INTO 120 VAC 

OUTLET 

SVk#SMm CATtACTX-K-0 $3.50 
8 3 Vdc «J 10 ma. CATH OCTX-831 $1 50 
12Vde©500ma.C«T«uCTX-12S $4.50 



12 Vdc 5 AMP 
POWER SUPPLY:; 



ACDC Electronics 

# !2.N5 orurjinv 

Input: 1 00 240 Vac 

(wired lor 1 1 5 Vac) 

Output: IZVdc 

© 5 amps, 

Open frame power supply. 

T X 4 W X 3- high. RegulateO" 

CAT* PS- 125 S37.50each 




NICKEL-CAD™ 
-BATTERIES V 
(RECHARGEABLE) 



AAASIZE $1.50 each 

1.2 volts 190 mAh 

CAT* NCa-AAA 

AA SIZE $2.00 each 

1 .25 volts 500 mAh 

CAUNCB-AA 

AA SIZE S2 20 each 

WITH SOLDER TABS 

CATtKCB-SAA 
C SIZE $4.25 each 
1.2 volts 1200 mAh 

CAT* NCR-C 

D SIZE $4.50 each 

1.2 volts 1200 mAh 

CAT* NCB-D 



XENON TUBE 



1" long tlashtube with 3 1/2" red 
and Hack laads. Ideal tor elec- 
tronic Hash or strobe projects. 
CAT*FLT-3 2 (or SI .00 



RELAYS 



6 VOLT D.C, - S.P.D.T. 
Aromat * RSD-5V 
Super small relay. 
Rated: 1 amp® 
30 Vdc. TTL direct drive possi- 
ble. Operates on 4.3 to 14 Vdc. 
Coil: 220 ohms. 1 3/16- X 1302" 
X7/16". CATtRSD-GV 
$1.50 each ■ 10 for SI 3 50 

12 VOLT D.C. 
D.P.D.T. 
DIP RELAY 
Miniature relay 
titsstandardi6pin [dip) sockets 
or will direclty mount to p.c. 
boards. Gl Clare* LM44D00 ■ 
2B0 ohm ■ 30 va switching. 
CAT*CRLY'12 $2.50each 

24 VOLT D.C. COIL | 
KUP style 
11 pin base 
can be socketed, 

direct soldered or quick 
connect terminals can be used. 

1 3/8" 1 1 1/2-1 2". 3.P.D.T, ■ 
5 amp contacts ■ 470 ohm 
CAT* HLY-3524 $2 25 each 



:0-6 HOUR AUTO 
SHUT-OFF TIMER 



M.H Rhodes, Ire Mark-Tin 
Timer his standard 
3" deep walbox Rated 
20 amps @ 125 Vac. Turn 
knob to desired lime. 
Includes hardware, beige 
wallplate, and knob. UL 
and CSA listed, CAT*TMC-6 
$5.75 each • 10 for $50.00 



1 



SPECIAL PURCHASE 

210MFD330V 

PHOTOFLASH CAPACITOR 



Rub+conCE photo! lash capacitor. 
079" dia. X 1.1" high. Those are 
new capacitors thai have been 

p rapped with 1.4" black and red K. J 

wire leads soldered to the terminals. 
CAT#PPC-210 $2 50 each 
10 far 522 50 ■ 100 for 5200.00 
Large quantities available. Call for pricing. 



STEPPER MOTOR 



Airpax P/N C82711-M1 /J^fl _? 

17 Vdc dual coil, 4-^=^4=^. 

permanent magnet stepper. ^N^tiC^ 
23.25 ohm coil. 7.5 degrees per step. 

C AT# SMT-6 $6 . 00 each • 1 for S50.00 



INSTRUMENT;: ENCLOSURES 



^ 



High quality molded ASS 
Instrument enclosures. 
Integrated PC board 
standoffs and iwo sets 

of vertical mounting slots for 
front and rear sub panels. All enclosures are 
6' wide X 6 1 M" deep. Choice or th re* h ts 
Includes non-skid rubber leel and hardware 
Available In beige, ivory, black, and blue. 

FliUahL CAT* 

21/4" CAT* MB- A S7.50 ucti lOfwSGS.CO 
2M" CATiMB-B *7. 73 each 10tffSG7 50 
3" CAT* M B- C 53 . CO ml* I Ear (70.00 

ptwso spejiiy color. 



RG-1 1/U 75 OHM VIDEO CA8LE 



100 ft or 200 ft rolls 
of RG 11/U terminated 
to heavy duly F connectors. 
I ncludea 75 oh rrt la rminator ^ ^ 9 m , , 
and F-01 spacer en one end. 
New cables manufactured ; cr ISM PC net- 
works. IBM P/N 1 501 BOS COM/SCOPE 
CAT#Ha-11-1 100ft roll S1 5.00 
CAT* HG- 1 1 -2 200 ft. roll $27. 50 



LED'S 



STANDARD JUMBO 
DIFFUSED T1-3Mti»(5mro) 



II 



RED CAT*LED-1 
IOforSI.50 ■ 100lorS13.00 

GHEEtf CAT* LEO-I 
IOtwS2.00- 100fori17.CO 

YELLOW C4TKLE0-3 
1 for $2.00 ■ tOO lor SI 7.00 

FLASHING LED 

win built in flKhfcig circuit 
5 voltepernion. T 1-3/4 (Smm) 
RED $1 i>; uch 

C*T#LED-4 10f«S9 50 />l 

GREEnf < 00 each J 

CAT# LED-4G 1 Igr I9.S0 ft 

YCLLOW ft 00 each I ' 

CAT* LED-4Y 10 f« J9.S0 

LED HOLDER 

Iwq 7: >■•■:.* holdw. 

CATttHLED 10fw65# 



3 



:PHotq;bes!stor 



fl 



100 ohmB bn'^iHkjht. 
ICKohmtdailt. 
C ■ •-.&2- cz X .Ofl'high. 0.1 JJ" long 
leAdt. CATK-PRE-T 2ic*S1 00 
100 lor 545 00 - 1000 f« S400 00 



OPTO SENSOR!! 



Standard U-»f><ep*>d JjUP 

stoned optical tMtch ■ ri 1 

WDMr'iB'^ipbfllWMn p| I' 

ad«o 7j" mounting zor.birz 
CAT#OSU-7 2lorS1.00 

HEFLECTIVEOPTO SENSORS 

ThujBO unitfi hava an IRemittw 

and tentx p«r pointing in the 

Mm* direction. Light from *rniHer 

bounce* oH object to b* detected 

by lor.ior Efffl^vfl-r-uigs appro* 
0.15V TTvee type* tvftitable. 

TRW/ Optron 
f OPB8447-3 

FUcta.n-guJu' 
w/ 2 S" wire Ivade 

CAT#OSfl-4 2 lor St .00 



tfT^fca 



TRWl Optron 

Jf OPB703A 

Wedg* th Bp* 

'.■.-.:;■. PC pint. 

CAT* OSR-3. TH "ch 

THW^Optfonff OPa7l1 j^^l 

Rfldangijar WtTt 

with PC pine. 

CATlrOSR-2 75f Mot. '" 



LEO, FLASHHR KIT:: 



Two L ED'S Hash in 
unison whren a 9 voU 
battery is attached. 
This kit includes a 
p.c. board, all the part* 
and instructions to maks a simple flasher 
circuit. A quick and easy prefect lor any- 
one wilh basic seta's ring skills. 
CAT*! LEDKIT $1 75 per kit 



!LED CHASER KIT:: 






Build this vanable 

speed ledcheser. 

lOWsftaflh 

sequentially at 

whatever speed 

you set them for. 

Easy to build kii includes po board, parts 

and instructions. Ideal for special lighting 

effects, costumes, etc. Operates on 3 to 9 

volts PC board is 5" X 2 25" A great one 

hour project. CAT* AEC S&SOeach 



STEPPING MOTOR 
CONTROLLER KIT 



Lsarn about 

Stepping 

motors white 

building the 

simple circuit. 

Includes circuit board, motor and all 

□arts except 12 Vdc power supply. 

CAT#SMKiT S1B,00each 



electroluminescent 
strip(OLow stripj;; 
an din verier;;; 



oik 



Used lor backighting control panels oi as 
decorative or emergency prime Ighling 
source. Tnin, tovgh And ' o>r'-.. tney oper- 
ate on low current AC voltage. The pro- 
lerred power source is a. miniature DC to AC 
inverter, These nave a bit of an odd shape. 
The strips are 2. IS" wide X J3 9 ft" Long and 
are 02S" thick. The luminescent area is 
5.3" long X 1.72" wide and hn one comer 
cut off, leaving a useful area ot fairly good 
proportions. We are selling the strips end In* 
vertere as a package. Inverter operates on 
G Vdc. Glow atrip, invefler and hook-up 
diagram CAT* GS-SQO $5 00per»t 

EXTRA INVERTERS 

I nput: 6 Vdc Output : 225 Vac 
CAT0INV-1 $2.00 each 



ORDER TOLL FREE 1-800-826-5432 



FAX (818) 781-2653 • INFORMATION (818) 904-0524 

Call Or Write For Our 




Free 60 Page Catalog 

Outside the U.S.A. send $2.00 
postage for a catalog. 



Minimum Order $10.00 'All Orders Can Be Charged To Visa, Mastercard 

Or Disccvercard • California, Add Sales Tax • Shipping And Handling $3. SO 

For the 48 Continental United States ■ All Others Including Alaska, Hawaii, 

P.R. And Canada Must Pay Full Shipping • Quantities Limited • No C.O.D. • 

Prices Subject to change without notice. 



m 



MAIL ORDERS TO: ALL ELECTRONICS CORP • P.O. BOX 567 • VAN NUYS, CA 91408 



CIRCLE 107 ON FREE INFORMATION CARD 



□ 
m 
O 
m 
S 

m 
31 



fJQ 

to 
o 



97 



J AMECO 



GoldStar 20MHz Oscilloscope 



S j^ss 



24 Hour Order Hotlin 
(415)592-8097 




Features: 

* 6" rectangular CRT dispEay. internal gratitude & Scale 

■ Phase difference measurements beiween two lorms under two methods: x-y scope 
and Dual Trace 

* Two dilferent scats probes : k1 and k 10 

■ Bandwidth Iron DC to 20MHz 

* Includes; Two 40MH2 probes, two loses, power cord, operation manual, schematics 
and block and wiring diagram 

* High sensitivity: imV/div 

* Two Year Warranty 



Jameco Logic Pulser 




■ Compatible with TIL DTL RTL HTL, 
HNIL. MOS and CMOS iCs. 

- 1 Mil Sync input impedance 

* "One shot" or continuous SHz train 
pulse 

■ Pulse repetition rale: O.5pps400pps. 

* Pulse width output at 1QQma load: 
10us 

* Pul$er mode output curreni: 10mA 

■ Square wave current outpus: 5mA 

* Audible tone 

* Siie:7.75"LK l"Wx.625"H. 

LP540 $16.95 



Jameco Logic Probe 




- Mas Frequency 8GMH* * Minimum delectable 
putee: ions >i£0Kii mpui impedance * Max. 
suppty voltage- '25V 1 * TTL HhreshokJ: (Lo)*0 SV 
dV (Hi) *2.3v -Q.2V ■ CMOS IhreshoW: (Lo) 
30% VCC 10% (Hi) 70%VCC -10% 

MS104 $24.95 



Metex Digital Multimeters 



General Specs: 

* Handheld, high 
accuracy ■ AC DC 

voftage. AC' DC 
current, resistance, 
diodes., continuity . 
Iran&islorhFE 

* Mpnual ranging w 
overload proieclion 




M3650 4 M46S0 only; 

* Aim measure Irequency and capacitance 

PROTOTYPING PRODUCTS M4650 only: - Data hold switch • 4.5 dtgil 
Jameco Solderless Breadboards 

M3G10 3 5 Dflit Multimeter 559.95 

_^^J* M3650 3 5 Cwgit Multimeter tt Frequency 5 

^^^^^\ Capacitance .»„♦. ,«,»»... S74.95 

\ ^^^. M4650 J 5 Digit ft Frequency. Capaetence 

\ ^^^\ and Daia hold Switch., $99,95 

V"*^ V^^ Handheld Multimeter 

.IF97 



3.5 diQ'l LCD with automatic polarity 
indicalion * AC DC voltage measurement up to 
500 volts ■ AC DC curreni measuremeni up 
to 200mA * Resistance measuremeni up lo 
2QMil - Conitnuity checker wiih audible lone 
• Diode and logic tester * Auto 'manual range 
and data hold Junctions - AN range 
protection and Junction indications 

DMM905 S49.95 





Pirl 


Dim. 


Coniacl 


Binding No. 






L" I W" 


Points 


Posls Price 




JE21 


325 i 2 125 


400 


$4.95 




JE23 


6.5 « 2 125 


830 


56.95 




JE24 


65« 3 125 


i 360 


2 $12.95 




JE25 


6 5 « i 35 


1.660 


3 $17,95 




JE26 


6 875 j 5.75 


2.390 


2 $22.95 




JE27 


imi* 


3.220 


J $32.95 



Jameco Universal IC Programmer 

Memory Devices: EPROMS, EEPROMS and PROMS 
Logic Devices: PALs, GALs, RALs, EPLDs, EEPLDs and FPLDs 




Stand alone or computer controlled mode via RS232C port 

The JE680 uses the JEDEC standard lor logic devices. Accepts input from 
virtually all major software packages including: PALASM. PLAN, CPUL, ABEL, and 
AMAZE 



.$1799.95 




• Programs all current EPROMs in the 2716 lo 
27512 range plus the X2864 EEPROM 
•RS232 port • Soltware included 

EPP ....$199.95 



UVP EPROM Eraser 



r 



- Erases all EPROM's ■ Erases 1 chip in 

15 minutes and 8 chips in 21 min 
• UV intensity: 6800 UW/CM 2 

DE4 $79.95 



Prototype 
Design Stations 



Features: - Removable solderless breadboard 

- Variable and fixed DC power supply • Multi- 
frequency signal generator • Analog multimeter 

- 8 bicolor LEDs (red & green) • 8 logic switches 

- Logic probe • Lighted power switch ■ Fuse 
overload protected ■ Pulse Generator • Binary 
coded decimal (BCD) to 7-segment decoder/ 
driver ■ DB25 connector • Frequency counter 
(1 Hz to 1 MHz) • Sturdy ruggedized case 



WM2 $299.95 




Soldering and Desoldering Stations 

60 Watt Analog Display Soldering Station • Electronic 
temperature control from 200= to 878"'F ■ Cartridge heat- 
ing elemeni for a longer lite of the soldering tip 

XY1683 $69.95 



30 Watt Electronic Temperature Controlled Desoldering 
Station ■ Electronic temperature control from 212" to 
842 ! F • Self contained high rotary vacuum pump 

XY999 $299.95 




CIRCLE 114 ON FREE INFORMATION CARD 



OuaWN 




i**** 



Cate\o9 






J AMECO 



£\eC 



yoV^ c 



jv\e^ s 



t ptoa^ cx l 






'art No. 
4LSO0 
4LS02 
'4LS03 


Integrat 

1-9 10+ 
.25 .15 
.25 .15 
.25 .15 
.25 .15 
.28 .18 
.59 .49 
,59 .49 
.28 .18 
.25 .15 
.29 .19 
.35 .25 
.49 .39 
.28 .18 
.29 .19 
.35 .25 
.28 .18 
.28 ,18 
.35 ,25 
.49 .39 
,85 .75 
.85 .75 
.39 .29 
.55 .45 
.49 .39 
.49 .39 


ed Circuits 

Part No. 
74LS154 
74LS155 
74LS156 
74LS157 
74LS158 
74LS166 
74LS169 
74LS173 
74 LSI 75 
74LS181 
74LS189 
74LS190 
74LS191 
74LS193 
74LS194 


1-9 

1.29 
.49 
.49 
.45 
.39 
.79 
.99 
.49 
.39 
1.39 
3.95 
.59 
.59 
.69 
G9 


10+ 
1.19 
.39 
.39 
.35 
.29 
.69 
.89 
.39 
.29 
1.29 
3.85 
.49 
.49 
.59 
59 


Mi 

Value 

43PXX 
63PXX 

PN2222 
PN2907 

f M4004 
2N2222J 

JMT123 
206-8 
MPC121 
MS102 

DB25P 
DB25S 

XC209P 
XC556C 


scellaneous Components 

Potentiometers 
s available (insert ohms into space marked ' 
SOOSi. IK, 5K, 10K, 20K. 50K, 100K. tMEG 


XX"): 

,,,.99 
....89 


4LS04 
'4LS05 
4LS06 
4LS07 
4LS08 
'4LS10 


Transistors 
12 1N473; 

12 I 2N390' 

.....10 ; 1N751 

^ 25 i C106B 

Swi 
SPOT. On-On (To- 
SPST, 16-pin (DIP 
SPDT.On-Otf-OnfT 
SPST, Momentary 

D-Sub Conne 

Male. 25- pin .65 

Female. 25 -pin.... 75 

L 

Tl.(Red) 14 

T! a «. (Greeni ...16 


And Diodes 

i 25 2N4401... 

1 12 1N4148... 

15 2N3055... 

1 49 MN270 

ches 


....15 

07 

... .69 
?5 

. 1.25 


'4LS1 1 


I 


.1.09 


'4LS13 
'4LS14 
'4LS20 
'4LS21 
4LS27 
'4LS30 
'4LS32 
'4LS38 
'4LS42 
'4LS47 
'4LS48 


(Push-Bulton} 

Dtors and Hoods 
DB25H Hood 


.1.19 
,39 


74LS221 

74LS240 

74LS241 

74LS323 

74LS541 

74LS590 

74LS670 

74LS688 

81LS95 

81LS97 


.69 

.59 

.59 

2.49 

1.09 

5.95 

.89 

2.19 

.99 

.99 


.59 
.49 
,49 

2.25 
,99 

5.75 
.79 

1.95 
.89 
.89 


EDs 

XC556R T1 3/4. (Red) 12 

XC556Y T1 3 /4. (Yellow) ...16 


IC Sockets 
Low Profile Wire Wrap (Gold) Level #2 

8LP 1 1 8WW .49 

14LP 12 14WW 65 


'4LS112 
'4LS122 
'4LS123 
'4LS125 


16LP 13 

24LP ....19 

28LP 22 

40LP 28 

Soldenail Standard & Head 


16WW 


.....69 


24WW 

28WW 

40WW 

ir Plug Sockets Also Av 


.1.05 
..1.29 
..1.79 

liable- 



Assemble Your own Computer Kit! 
Jameco 16MHz 80386SX Desktop Computer Kit 



■ Building your own computer provides you with a better understanding of 
components and their functions 

■ In-depth assembly instructions included 

■ Have your new computer assembled and running in three hours, 
using common tools 

■ Software included 

■ Purchase computer kits configured by Jameco or design your own 



Jameco 16MHz 80386SX 
Desktop Computer Kit 

Includes: 

• 80386SX Motherboard with 
2MB RAM (expandable to 8MB) 

• 1 01 -key enhanced keyboard 

• Mulli I/O Card 

• Toshiba 1.44MB. 3.5" DSHD 
floppy disk drive 

■ Baby si2ed desktop case 

• 200 Watt power supply 

■ DR DOS (Version 5,0) by 
Digital Research and Diagsoft's 
QAPIus diagnostic software 









$1199.95 



JE3816 




■ 



Hard 

Drives 



Conner (16-bit IDE) 

CP3044 10MB 3 5" Low Prolple $469.95 

CP31 84 8MB 3.5'HH... $699.95 

CP3104 1MMB 3.5 - HH... $799.95 




ADP20 Hosi Afliaprer... 



..$29.95 



Relisys 14" VGA 
Color Monitor 




• Max resolution: 720 x 480 
■ Bandwidth: 30MHz 
« Tilt/Swivel base 

RE9513 $449.95 

Jameco 16-bit VGA Card 




• Supports VGA, EGA. CGA. MDA and 
Hercules modes ■ Comes with 256KB 
uideo RAM upgradable to 512KB (eight 
41464-80) • Capable of B40 x 4S0 with 
256 colors. BOO x 600 with 16 colors 

VG2000 $149.95 



24 Hour Order Hotline 
(415)592-8097 



Look to Jameco. 



• Wide selection of integrated 
circuits and components 

■ Quality prototype and test 

equipment 

Additional items that Jameco offers; 

■ Hard Drives 

• Motherboards 

- Memory Modules: 

• SIPPs 

• SIMMs 

■ NEC V20 and NEC V30 Chips 
. RAMa 

■ Math Coprocessors 

• Computer Kits 

• Integrated Circuits 

• Components 

■ Much, much more ! 



Let us show you what we have to otter; 
catt or write tor the iatest Jameco catalog! 



24 Hour Order Hotline 
(41 5) 592-8097 

FAX'S: (415) 592-2503 

or (415) 595-2664 
Telex 176043 

1355Shoreway Road 
Belmont, CA 94002 

$50.00 Minimum Order 
Data Sheets - 50c each 

Far a FREE 90-Page catalog send $2.00 to cover 
tirsl Class Postage and Handling 

1990 Jameco Eleciranics IZ'SKl 

CA Residents Add 
6.25%, 6.75% or 7.25% Sales Tax 

Shipping - Add 5% plus St. 50 Insurartce 
i May va*y according ;o weigm and snipping memod) 
Terms; Prices subject to change wilhoul nolice. 
li ems subject lo availability and prior sale. 

CdftipleLa iisi -of [<Kms.warTam.Gs is available upon Toques! 
IBM is m registered smOainiH* el Internananni Busmen ttotrni'ea 



VISA 


MMC 


Q$ 


__ MtHSf a 



Please 
reEer to 
Mail Key 2 
when 
Ordering 



CIRCLE 114 ON FREE INFORMATION CARD 




GRA1- ANT I GRAVITY GENERATOR .. .S1OJ00 

m LC7 — 40 WATT BURNING CUTTING LASER . . 52O00 

= * RU B4 - HI POWEfi PULSED DRI LUNG LASER S20.00 

topBTCS- 1 MILLION VOLT TESLA COIL S2M0 

ESKMCP1- HI VELOCITY COIL GUN . $15.00 

2 3 LLS1 - LASE P. LIGHT SHOW 3 METHODS $20.00 

ty>EH1- ELECTRONIC HYPNOTISM TECHNiOJES . . .SSflO 

2 EML1 - LOWER POWERED COIL GUN LAUNCHER S5.00 

3JL3- JACOB LAODER 3 MODELS . 510.00 

SDS- SEEINTHEDARK $10.00 

Q-LEV1- LEVITATI OK DEVICE . . $10.00 

Ufr-MVIK -3 MILE FM VOICE TRANSMITTER $3450 

3 PF S1 K - WW CONTROLLED- PLASMA FIRE SABE R $4950 

5 NIGTK - HI FLUX NEGATIVE ION GENERATOR $3450 

£«PG5K- PLASMA LIGHTNING GLOBE $4950 

= | IHC2K- VISIBLE SIMULATED 3 COLOR LASER .. .$4450 
g= H0D1K- HOMING/TRACKING BEEPER TRANSMITTER $44.50 
gff IBUHC— 25 MW HAND-HELD VISIBLE LASER GUN $24950 

3 £ BTC3K - 250,000 VOLT TABLE TOP TESLA COIL . . . $249.50 
CO I0GZK — ION RAy GJN , praiect erierjy without wires $129.96 
r— TK E1 K - TELEffll E TIC E NHANCE WELECTRIC MAN . . SMO 
2 VWPM7K - 3 MILE AUTO TELEPHONE TRANSMITTE R . $4950 

q ASSEMBLED IN OUH LABS 

Uj LIST10 - INFINITY XMTR Lislen in via phone lines . S199.50 

J IPG70 — INVISIBLE PAIN FIELD BLASTWAVEGENEHAT0RS74.rJ0 

DO ITM10 - 100,000 VOLT INTIMIDATDR UP TO 20' $99.50 

S TAT30- AUTOMATIC TELEPHONE RECOROlNGDLvlCE 524.50 
UJ PSP40 - PHASOR SON IC BLAST WAVE PISTOL . , . $89.50 
M MEW— AU.NEW 28" VWB COLORED NEON STICK ,574.50 
CO LGU2Q - 5 TO 1 MW VISIBLE REO HeNe LASER GUN 519*50 
^BLS10- 100JX) V*ATT BLASTER DEFENSE WAND . $8950 

EASY 0RDEH1NG PROCEDURE - TOLL FREE 1-BD0-22 1-1705 

or 24 HRS ON 1-H&673-4730 or FAX IT TO t-603-672-5406 

VISA. MC. CHECK, MO IN US FUNDS. INCLUDE 10% SHIPPING. ORDERS 

5100.008 UPONLY AOD $10.00. CATALOG $1.00 OR FREE WITH ORDER. 



INFORMATION UNLIMITED 

P.O. BOX 716, DEPT. R2, AMHERST. NH 03031 



CO 

o 

O 

X 

F 
o 

LU 
~J 
UJ 

g 

< 

EC 

100 



COMPUTERS FOR LE$$ 



JCI 10 MHz 8088 System $399.00 

• 10 MHz Motherboard w/WOKB RAM 

• Math Co-Processor Socket 

• One 5.25" 3«0 KB Floppy A Controller 

• 101-Key Enhanced Keyboard 

• lSOWatlPowerSupplyJtCase 

• MonoGraphica Card w/ Parallel Port 

• 12? Amber Monochrome Monitor 



JCI Standard Configuration: 



1 MB RAM on board ©Wait Stale 
Built-in Real Time Clock & Calendar 
Math Co-Processor Socket 

One 1.2 MB or 1.44 MB Floppy Drive 
1:1 Hard I Floppy Disk Controller 

2 Serial, J Parallel, and 1 Game Port 
101-Key Enhanced Keyboard 
Deluxe Case w/ 200 Watt Power Supply 
MonoGrapbks Card w/ Parallel Port 
12" Amber Monochrome Monitor 



JC1 12 MHz 80286 System $ 649.00 

JC1 16 MHz 386SX System $ 869.00 

JCI 20 MHz 80386 System $1149.00 

JCI 25 MHz 386 32K Cache $ 1495.00 

JCI 33 MHz 386 32K Cache $ 1850.00 

Please Call For Custom Configurations 



One Year Parts & Labor Warranty 

30 Day Satisfaction Guarantee 

Shipping & Handling Extra 

VISA & WC add 3% Amex add 4% 

JINCO COMPUTERS INC. 

5122 Walnut Grove Avenue 

San Gabriel, CA 91776 

Tel: (81 8) 309-1 1 08 - Fax: (81 8) 309-1 1 07 



ADVERTISING INDEX 



RADIO-ELECTRONICS does not assume any responsibility for errors that may appear in 
the index below. 



Free Information Number 



imt 
75 
1 07 
1 93 

77 
67 

ys 

1 09 

70 

187 

1 76 
184 

55 
58 
188 

1% 

127 
198 

177 

121 
189 

86 
185 

114 
104 

178 



53 
93 
61 

186 

56 

197 

179 



Page 

AMC Sales „y 

Ace Products 62 

All Electronics 97 

Alpha Products , 75 

Amazing Concepts 1 IK) 

li&K Precision CV4 

Banner Technical Books 90 

Beckman Industrial 14 

C&S Sales 5 

CE1 94 

l. i Hi .... , , , , , , . 1 1 . ^j 

Chenesko Products 62 

Command Productions 89 

Communications Specialists 79 

CompuServe CV3 

Contact East 2K 

Cook's Institute ii I 

D&D Electronics 77 

Damark International 17 

Datak Corporation 28 

Deco Industries 62 

EKI 37 

Electronic Goldmine 94 

Electronics & Engineers B.C. . . .82 

Fluke Manufacturing CV2 

Global Specialties 12 

Grantham College 56 

Heathkil 29 

How to Book Club 7 

ISCET 81 

Jameco 98,99 

Jan Crystals 89 

Jinco Computers 100 

King Wholesale 92 

Lindsay Publications 73 

Ml) Electronics. 92 

Mark V. Electronics. 93 

Microprocessors llnlld 87 

NK1 Schools 18 

Optoelectronics 39 

Parts Express 95 

Pholronics, Inc 62 

Probemaster ..31 



78 Radio Shack 32 

190.191 SCO Electronics 72 

194 Sencore 27 

— Star Circuits 31 

192 TECI 79 

123,180 Test Probes 3 

225-228 Test Probes 3 

195 Unicorn 96 

181 Viejo Publications 90 

182 WIT Publications 79 

183 Xandi Electronics 62 



ADVERTISING SALES OFFICE 

Gemsback Publications, Inc. 
500-B Bi-County Blvd. 
Farmingdale, NY 11735 
1(516) 293-3000 
President: Larry Steek let- 
Vice President: Cathy Steekler 

For Advertising ONLY 

516-293-3000 

Fax 1-516-293-3115 

Larry Steckler 

publisher 
Arline Fishman 

advertising director 
Denise Haven 

advertising assistant 
Christina Estrada 

advertising associate 
Kelly McQuade 

credit manager 

Subscriber Customer Service 

1-800-288-0652 

Order Entry for New Subscribers 

1-800-999-7139 

7:00 AM - 6:00 PM M-F MST 

SALES OFFICES 

EAST/SOUTHEAST 

Stanley Levitan, Eastern Sales Manager 

Radio-Electronics 

259-23 57th Avenue 

Little Neck, NY 11362 

1-718-428-6037, 1-516-293-3000 

Fax 1-718-225-8594 

M I D WE ST/Texas/ Arka ns a s/O kla . 

Ralph Bergen, Midwest Sales Manager 

Radio-Electronics 

540 Frontage Road— Suite 339 

Northfield, IL 60093 

1-708-446-1444 

Fax 1-708-446-8451 

PACIFIC COAST/ Mountain States 

Marvin Green, Pacific Sales Manager 

Radio-Electronics 

5430 Van Nuys Blvd. Suite 316 

Van Nuys.CA 91401 

1-818-986-2001 

Fax 1-818-986-2009 



CIRCLE 178 ON FREE INFORMATION CARD 




There's nothing newabout having everything 

^- Oft f o /. o 

you need inoneplace. 





■ > -=» ^- 'T* -. ■^r^-'" J - = , 1 ' 



WithCompuServe, it's all at your fingertips. 



When you become a member of 
CompuServe, you join a vital, 
active community of over 500,000 
friends and neighbors from all over 
the world. 

Small-town friendly We 
keep in touch with electronic mail 
and faxes, and by posting messages 
on our bulletin boards. We even meet 
in forums to discuss everything 
from science fiction to sharing 
software, and to get invaluable 
personal computer software 
and hardware support. And that's 
one of the best things about small 
towns: people helping people. 

Big-city opportunities, But 
we can also shop coast-to-coast 
at hundreds of nationally known 
stores, and take advantage of a 
world-class library We have 



access to the latest 
national and interna- 
tional news, And our 
special financial files 
offer complete statistics 
on over 10,000 
NYSE, 




AMEX, and OTC securities. 

We can even trade online with 
our local discount brokers. 

And, just for fun . . . We ve 

also got games — everything from 
trivia to TV-style game shows with 

CIRCLE 184 ON FREE INFORMATION CARD 



live entertainment to interactive 
space and fantasy adventures, 

We've got airline schedules, 
so you can check out the bargains 
and book your own flights online. 
We even have listings from over 
35,000 hotels. 

It's not hard to get here, To 
get to CompuServe, all you need 
is a computer and a modem, We'll 
send you everything else, includ- 
ing a $25.00 Usage Credit. In most 
places you'll be able to go online 
with a local phone call. 

To buy a CompuServe Mem- 
bership Kit, see your nearest 
computer dealer, To receive our 
informative brochure or to order 
direct, call 800 848-8199. 

CompuServe 



Notice any difference 
between these two 
DC power sources? 

























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-PRECIS 








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mt+m 




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Your budget sure will! 



B&K-PRECISION power supplies cost less than other 

power supplies you may be used to buying, but to your circuits 
they look identical. Your circuit will see only the same pure, 
clean DC power that comes From the high-priced lines. You'll 
see the savings. 

B&K-PRECISION builds DC power supplies for most bench appli- 
cations requiring up to 10 amps. All are fully regulated with excel- 
lent ripple and noise characteristics. Some models feature digital 
metering, multiple outputs, tracking and constant current operation. 



Start saving cash on your next power supply purchase. 
Compare features, performance and price and you'll choose 
B&K-PRECISION. For a free Power Supply Selection Guide 
or immediate delivery, contact your local distributor or 
B&K-PRECISION, 




Front row left to right: Model 1660 $629, 

Model 1610 $215, Model 1630 $315, 

Model 1635 $365. Back row top; Model 1601 $485, 

Model 1646 $489; Bottom: Mod# 16"Sb,$510. 

CIRCLE 77 ON FREE INFORMATION CARD 




M AXTEC INTERNATIONAL CORP. 

Domestic and International Sales 
B47D W. Cortland St., Chicago, IL 60635 
312-889-1448 • FAX: 312-794-9740 
Canadian Sales, Atlas Electronics, Ontario